The most common another word for “which” is “that” , but the best alternative depends on how you’re using it.

Below is a quick, SEO‑friendly “Quick Scoop” style breakdown.

Another Word for Which

1. Quick Answers by Usage

A. When “which” starts a question

Examples: “Which book?”, “Which one do you prefer?” You can sometimes use:

  • what – “What book do you prefer?” instead of “Which book do you prefer?”
  • which one – a slightly longer but natural variant: “Which one do you like?”

In casual conversation, “what” is the most natural swap when you’re asking about options in general.

B. When “which” links clauses (relative pronoun)

Examples:

  • “The car, which was red, sped past.”
  • “The method which he used was risky.”

Possible alternatives:

  • that – “The method that he used was risky.” (very common in modern English)
  • who / whom – only for people: “The teacher, who was kind, helped me.”
  • whatever / whichever – when you mean “any that”: “Use whichever method works best.”

Writers also often restructure the sentence instead of swapping a single word:

  • “The method he used was risky.” (removing “which/that” entirely)
  • “He used a risky method.”

2. Mini Section: “Which is” Alternatives

If you’re looking for “another word for which is ” in the middle of a sentence, you usually replace the whole phrase, not just “which”.

Common options:

  • that is – “The car, that is red, is mine.” (more natural: “The car that is red is mine.”)
  • , a … that – “Solar power, a technology that uses sunlight, is growing quickly.”
  • and or as – “He chose the second option, as it seemed safer.”

3. Tiny Usage Guide (So You Don’t Overthink It)

Use this quick decision path:

  1. Are you asking a question?
    • Talking about options in general → try what.
    • Emphasizing a specific set of choices → keep which or say which one.
  1. Are you linking extra information to a noun?
    • Everyday writing → that is usually fine instead of “which”.
 * Talking about a person → use **who** / **whom**.
  1. Does the sentence feel clunky?
    • Remove “which” or rephrase the whole clause instead of forcing a synonym.

4. Short Example Set

  • Question: “Which movie are we watching?” → “What movie are we watching?”
  • Relative clause: “The plan, which was risky, failed.” → “The risky plan failed.”
  • Technical/formal: “The device, which is powered by electricity…” → “The device, a unit that is powered by electricity…”

TL;DR:

  • what for many questions.
  • that for many relative clauses.
  • who/whom for people, whichever/whatever for “any that,” or just rewrite the sentence when “which” sounds repetitive.

Information gathered from public forums or data available on the internet and portrayed here.