Noun Verb Adjective A2–C1 /beɪs/

Base — Definition, Examples & Usage

The bottom, the starting point, the foundation — one of English's most versatile words.

Quick Definition

Noun

The bottom or lowest part of something; the headquarters of an organisation or military unit; a starting point or foundation for something.

Verb

To use something as the foundation or starting point for something else. "The report is based on recent research."

Adjective

Fundamental; or, in formal and literary use, without moral principles; ignoble.

What Does Base Mean?

Base is one of the most productive words in English. It comes from Latin basis (a pedestal or foundation) via Old French base, entering Middle English in the late 14th century. That same Latin root gives us basis, basic, basement, baseball, and the suffix -based (London-based, evidence-based).

As a noun, base can be concrete — the base of a column, the base of a mountain — or abstract — a customer base, a knowledge base, a tax base. In military and scientific contexts it refers to a headquarters or a reference point. In chemistry it is the opposite of an acid.

As a verb, base almost always appears in the passive construction be based on: "The film is based on a novel." The active form exists but is less common: "We based our argument on the available data."

As an adjective, basic (not base) is the normal everyday form. The adjective base is used formally or in set phrases such as base instincts or base motive, meaning morally low.

Usage tip: Do not confuse base (concrete/physical bottom, or headquarters) with basis (abstract underlying principle). You write on the basis of the evidence but the base of the statue. A common learner error is writing "on the base of" when "on the basis of" is required.

Etymology

From Latin basis "pedestal, foundation", borrowed from Greek basis "a step, pedestal", from bainein "to walk, to step". The adjective sense ("morally low") derives from a separate Latin root bassus "short, low", which also gives French bas and Italian basso. Both branches entered Middle English in the 14th century, merging into the single spelling base.

Example Sentences

Sentence Level Usage note
The lamp has a heavy stone base. A2 noun — physical bottom
The soldiers returned to their base after the mission. B1 noun — military headquarters
The report is based on recent research. B1 verb — passive: be based on
The company has built a loyal customer base over two decades. B2 noun — abstract: customer base
The philosopher argued that self-interest was the base motive behind all seemingly generous acts. C1 adjective — formal: morally low

Collocations

Collocation Example
base camp The climbers set up base camp at 4,000 metres.
base salary The base salary is £32,000, with bonuses on top.
base rate The Bank of England raised the base rate by 0.25 per cent.
customer base The start-up grew its customer base rapidly in the first year.
knowledge base The support team maintains an online knowledge base for users.
tax base The government sought to widen the tax base to fund public services.
home base London remains the company's home base despite its global reach.
based on The new policy is based on the committee's recommendations.
evidence-based The treatment protocol follows an evidence-based approach.
touch base Let's touch base next week to see how things are progressing.

Usage Notes

Base vs basis: Use base when you mean the physical bottom of something or a concrete headquarters. Use basis when you mean the abstract foundation for an argument, decision, or relationship. The phrase is always on the basis of, never on the base of.

Based in vs based at: Use based in for cities or countries ("She is based in Edinburgh") and based at for a specific building or site ("The team is based at the Canary Wharf office").

Touch base: This common business idiom means to make brief contact with someone to share information or check progress. It comes from baseball. It is informal and best avoided in formal writing.

Base as adjective: In modern British English, the adjective sense meaning morally inferior is rare outside literary or formal contexts. Do not use it to mean "basic" — that job belongs to the word basic.

Common Mistakes

Watch Out For

The decision was made on the base of the survey results.

The decision was made on the basis of the survey results. (basis, not base, for abstract foundations)

The film bases on a true story.

The film is based on a true story. (use the passive be based on)

She has a very base knowledge of grammar.

She has a very basic knowledge of grammar. (basic for "elementary"; base as adjective means "morally low")

Related Words

basis basic basically basement baseline based database foundation bottom ground

Practise This Word

Flash Cards Complete the Sentence Vocabulary Quiz Hangman

Frequently Asked Questions about “base”

What does base mean in English?
Base has three main uses. As a noun it means the bottom or lowest part of something ('the base of the mountain'), or a headquarters or starting point ('a military base'). As a verb it means to use something as a foundation ('The film is based on a true story'). As an adjective it means fundamental or, in formal use, lacking moral principles ('a base motive').
What is the difference between base and basis?
Base is most commonly used as a concrete noun referring to a physical bottom or a headquarters: 'the base of the lamp', 'an army base'. Basis is an abstract noun meaning the underlying principle or reason for something: 'on the basis of the evidence'. You cannot freely swap them — a report is written 'on the basis of research', not 'on the base of research'.
How do you use based on correctly?
'Based on' is a phrasal adjective meaning derived from or supported by something. It normally follows a noun or passive verb: 'a novel based on real events', 'The decision was based on incomplete data.' Avoid the construction 'basing on' or 'base on' without the passive — 'The film bases on a true story' is incorrect. The correct form is 'The film is based on a true story.'
What are common collocations with base?
Common noun collocations include: base camp, base rate, base salary, knowledge base, customer base, tax base, and home base. Common verb collocations include: establish a base, build a base, expand a base, and return to base. The phrase 'base one's argument on' is widely used in academic writing.
What is the difference between base and basic?
Base as an adjective is formal and literary, usually meaning morally low or without principle ('base instincts'). Basic is the everyday adjective meaning fundamental, simple, or forming a starting point ('basic vocabulary', 'basic needs'). In most everyday situations, basic is the word you want rather than the adjective base.
What is the plural of base?
The plural is bases (pronounced BAY-siz). Be careful not to confuse it with the plural of basis, which is also spelled bases but pronounced BAY-seez. Context usually makes clear which word is meant: 'military bases' (noun plural of base) versus 'on different bases' (plural of basis).
Is base a regular verb?
Yes. Base is a regular verb: base, based, based. It is most commonly used in the passive voice: 'The theory is based on extensive fieldwork.' In the active voice you would say 'We based our proposal on the latest figures.' The gerund form is basing: 'Basing your argument on assumptions is risky.'
What does off base mean?
'Off base' (or 'off-base') is an idiom, chiefly used in North American English, meaning incorrect or mistaken: 'Your estimate is completely off base.' It originates from baseball, where a runner caught off base is out. In British English, 'wide of the mark' or 'off the mark' conveys a similar meaning.
What is the origin of the word base?
Base as a noun comes from Latin 'basis' (foundation, pedestal) via Old French 'base'. The Latin word was itself borrowed from Greek 'basis', meaning a step or pedestal, from the verb 'bainein' (to walk, to step). It entered Middle English in the late 14th century. The adjective sense meaning morally low comes from a separate Latin root, 'bassus' (short, low).
How can I practise the word base in English?
LexFizz's Complete the Sentence exercise includes high-frequency words like base used in realistic contexts. You can also try the Flash Cards tool to review base alongside related words such as basis, basic, and based. Pay special attention to the collocation 'based on', which appears frequently in academic and professional writing.