Past Tense of “know”
The past tense of know is knew; the past participle is known.
Why “know” behaves this way
"Know" descends from Old English "cnawan," part of a small, ancient class of Germanic strong verbs that originally formed their past tense through reduplication (like "do/did") before that pattern reanalyzed into a simple vowel change over time. The silent "k" in "know," "knee," and "knife" is a genuine fossil of Old English pronunciation — the /k/ was fully pronounced in Old and Middle English (cnawan really did start with a hard k sound) and only stopped being pronounced in English around the 17th-18th centuries, well after the spelling had already been fixed.
"Know" is distantly related, through Proto-Indo-European, to the Latin root behind "cognition" and "recognize," and to the Greek root behind "gnosis" — all ultimately going back to the same ancient root meaning "to know" or "to recognize," which is why English ended up with both a native Germanic word (know) and a whole family of Latinate/Greek-derived academic vocabulary (cognitive, gnostic, notion) built on the same underlying concept.
The common confusion
The confusion with "know" is almost entirely about "knew" vs. "new," a true homophone pair (or near-homophone, depending on accent) that has nothing to do with grammar and everything to do with the silent-k spelling colliding, in pronunciation only, with an unrelated word.
How it's actually used
"Know" belongs to the small class of "stative verbs" — alongside "understand," "believe," and "want" — which describe a state rather than an action and therefore resist the progressive -ing form in standard usage. "I am knowing the answer" sounds wrong to native ears in a way that "I am running" doesn't, because knowledge is treated grammatically as a state you're in, not an activity you're doing. "Know" also combines with "how to" to describe an acquired skill rather than factual information — "I know how to swim" describes ability, distinct from "I know that swimming is good exercise," which describes a fact — two grammatically different complement patterns riding on the exact same verb, both worth distinguishing since confusing them produces awkward, non-native-sounding sentences.
Across the tense system
The perfect tenses of "know" ("have known," "had known") are unusually common in everyday speech because "know" describes an ongoing state rather than a single event — "I have known her for ten years" describes a state that started in the past and continues now, a use of the present perfect that's genuinely different from "I have finished my homework," which describes a single completed event. The negative present tense of "know," "don't know," is also one of the most frequent hedging phrases in spoken English ("I don't know if...", "I don't know why..."), used constantly to soften a claim or admit uncertainty in conversation, a discourse function distinct from its literal meaning of lacking factual knowledge.
Common real mistakes
A subtle but real error is using "know" in the progressive ("I am knowing the answer"), which sounds wrong to native speakers because "know" is a stative verb describing a state of mind rather than an ongoing action — the correct form is simply the present simple, "I know the answer." Learners occasionally also confuse "know" with "meet" when describing first encounters — saying "I knew him at the conference" to mean a first introduction, when English reserves "know" strictly for an ongoing state of acquaintance and requires "met" for the specific event of first encountering someone ("I met him at the conference; I've known him ever since").
Examples
- I knew the answer before she finished the question.
- He has known her since college.
- We knew it was going to rain.
- Have you ever known anyone like that?
- They had known each other for years before dating.
- She knows this city better than anyone.
- You never know what might happen.
- I don't know him personally.
Memory trick
Keep the silent "k" in mind as a leftover sound, not a decoration — it's the same fossil letter in "knee" and "knife," all once pronounced, now silent, and all distantly related to "recognize" through the same ancient root.