Meaning
Literal: To literally direct your eye (vision) toward something and maintain attention on it — keeping watch.
Figurative: To watch, supervise, or monitor something or someone carefully, often over a period of time, to ensure safety, correctness, or that nothing goes wrong. It implies ongoing vigilance rather than a single glance.
Origin & History
This idiom uses the eye as a symbol of attention and vigilance — a metaphor deeply rooted in many cultures. The phrase treats the eye as an instrument of care and oversight. The singular "an eye" (rather than "both eyes") is characteristic of many English idioms involving vision, suggesting focused, dedicated attention.
The expression has been in common use in English since at least the 18th century and appears widely in literature. It reflects a broader family of "eye" idioms in English — "turn a blind eye", "see eye to eye", "catch someone's eye" — all of which use the eye as a metaphor for awareness and perception. Today "keep an eye on" is one of the most common idiomatic phrases in everyday British and American English.
Example Sentences
| Context | Example |
|---|
| Childcare | "Could you keep an eye on the kids while I make a phone call?" |
| Workplace | "Management is keeping a close eye on the project's budget this quarter." |
| Cooking | "Keep an eye on the pasta — it'll only take eight minutes." |
| Finance | "It's worth keeping an eye on interest rates over the next few months." |
How to Use It
Register: Neutral — comfortable in both informal conversation and professional contexts. More formal alternatives include "monitor", "observe", "supervise", or "track".
Grammar patterns: "Keep an eye on + noun/pronoun/gerund": keep an eye on the situation / keep an eye on him / keep an eye on what is happening. The verb "keep" is conjugated: keeps, kept, keeping, will keep.
Variation: "Keep a close eye on" adds emphasis, suggesting even more careful monitoring. "Keep an eye out for" (slightly different meaning) means to watch for the appearance of something.
Common Mistakes
Watch out for these errors
"Can you keep an eye at the bags?" (wrong preposition — use "on", not "at")
"Can you keep an eye on the bags?"
"She keeped an eye on the children." (irregular verb — past tense of "keep" is "kept")
"She kept an eye on the children."
"Please keep eyes on the entrance." (the fixed idiom uses the singular: "an eye")
"Please keep an eye on the entrance."
Similar Idioms
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Frequently Asked Questions
What does "keep an eye on something" mean?
It means to watch or monitor something or someone carefully and attentively, making sure that everything is safe, correct, or progressing as expected.
Can "keep an eye on" refer to a person?
Yes, the idiom can be used for both people and things. "Keep an eye on the children while I'm out." / "Can you keep an eye on my bag?" The object simply changes from a thing to a person.
What is the difference between "keep an eye on" and "watch"?
"Watch" is the plain verb equivalent, but "keep an eye on" carries a slightly warmer, more informal tone. It also suggests ongoing vigilance over a period of time, rather than a single focused act of watching.
Is "keep an eye on" formal or informal?
It is neutral to informal. It is perfectly natural in everyday conversation, emails between colleagues, and parenting contexts. It would be replaced by more formal language such as "monitor" or "observe" in official or academic writing.
What does "keep an eye out for" mean?
"Keep an eye out for" is a related idiom meaning to actively look for something or be alert for its appearance: "Keep an eye out for a parking space." It differs in that it involves searching or waiting for something to appear rather than monitoring something already present.
Can you say "keep your eyes on something"?
Yes, "keep your eyes on something" is a natural alternative meaning to focus visual attention on a specific thing: "Keep your eyes on the road." However, "keep an eye on" (singular "eye") is the standard idiomatic form used to mean ongoing monitoring or supervision.
What are other idioms with "eye"?
Common eye idioms include: "turn a blind eye" (deliberately ignore), "see eye to eye" (agree with someone), "an eye for an eye" (revenge), "catch someone's eye" (attract attention), "in the blink of an eye" (very quickly), and "keep an eye out for" (watch for something).
What CEFR level is "keep an eye on something"?
"Keep an eye on something" is a B1 (Intermediate) idiom. It is one of the most common idioms in everyday English and is likely to be encountered regularly by learners at this level.
How do you use "keep an eye on" in the past tense?
The verb "keep" is irregular. Past tense: "kept". So: "I kept an eye on the bags while she was in the shop." / "He had kept an eye on the situation all morning."
What is the opposite of "keep an eye on something"?
Opposite expressions include "ignore", "neglect", "take your eye off something", or "let something slide". The phrase "take your eye off the ball" is a related idiom meaning to stop paying attention to what is important.