Some comparatives are irregular. What's the comparative of 'good'? 'This one is ___ than that.'

"Better" is the irregular comparative form of "good," meaning English simply doesn't follow its usual pattern of adding "-er" to this particular adjective the way it does for words like "faster" or "taller." Instead, "good" borrows an entirely different word root for its comparative and superlative forms, a phenomenon linguists call suppletion.

"Gooder" isn't a recognized English word at all, since "good" never takes the regular "-er" ending. "Best" is the superlative form, used when comparing three or more things to identify the single top one, not the comparative form used for comparing just two things.

Suppletion — where a word's forms come from historically unrelated roots — also shows up in "bad/worse/worst" and "go/went," reflecting how heavily used, ancient words often resist the regular grammatical patterns that newer or less common words follow.