Analogy Solved: Brook : River :: Stream : River

The answer to the analogy **"Brook is to river as blank is to river"** is **stream**.

Why?

• A **brook** is a **small stream** — a minor, often tributary watercourse.
• A **stream** is the **general term for a flowing body of water** smaller than a river.
• **Brook ≈ Stream** (near synonyms in common usage; brook implies smaller, more rustic).
• Both are **hyponyms (subtypes)** of **river** in the hierarchy of flowing water:

River (largest, main stem)
  ↑
Stream (general term for smaller flowing water)
  ↑
Brook / Creek / Rill / Run / Kill / Burn (regional/dialect terms for small streams)

Analogy Structure

Specific instance : General category :: General term : General category

• Brook : River → A *type of small stream* is to the *main river*.
• Stream : River → The *general category of small flowing water* is to the *main river*.

Both pairs express a **size/hierarchy relationship** within a drainage network. "Creek" would also work regionally (US/Australia), but "stream" is the universal hydrological term.