不是很grammar point · tier 2 · 不是很 hedged negation (not very / not entirely)
Sets 不是 in front of a degree-marked quality (很 + stative) to deny that it reaches the high mark, leaving the quality in a soft middle. Reads as a tentative, face-saving 'not entirely / not quite', gentler than docking the degree outright.
字源 FORM what the parts do
不 is the borrowed bar that turns a thing back. 是 is the sun (日) over straight (正) — the sign that holds a statement as so. 很 raises the quality to a high mark. 不是 bars the sign before the whole raised claim, so what gets denied is that it stands true all the way up, not the quality itself.
故事 STORY a scene to remember it by
A claim climbs toward the top mark, and the bar lands on the claim itself, not the quality — leaving it standing in the middle, neither all the way up nor knocked to the floor.
字源記憶法
框 · Frame
[subj] 不是 (很 / 太) [stative verb / VP]
觸 · Trigger
You want to back off a judgment gently — to say something falls short of 'very', softer and more tentative than a plain 'not'.
序 · The move
1Name the quality as a gradable stative verb or VP (清楚, 同意, 好).Can it have more or less — something a high mark would push up?
2Raise it with 很 (the default; 太 in some frames), then bar the whole claim with 不是 in front: 不是很清楚.Is 不是 sitting before the degree word, denying the raised claim — not before a bare noun (不是學生, the copula)?
3Read the result as a soft middle, not a flat no.Does 不是很清楚 mean 'less than fully clear', not '不清楚' (unclear outright)? If you mean a hard no, drop to bare 不 / 沒.
例 · Examples
1這句話的意思不是很not entirely / not quite清楚clear，可以說明explain一下嗎？
The meaning of this sentence isn't entirely clear; could you explain it a little?
界 · Boundary
不太 / 不很
不太清楚 docks the degree directly — falls short of clear. 不是很清楚 bars the whole claim that it reaches clear — one extra remove, more tentative and face-saving. 不是很 hedges the assertion; 不太 hedges the amount.
不是學生 denies an identity — A is not B, 不是 before a noun. 不是很清楚 denies a degree-marked quality — 不是 before 很 + a stative. The slot after 不是 tells them apart: noun gives the copula, degree word gives the hedge.
不清楚 is flatly unclear, the quality denied outright. 不是很清楚 leaves it partly clear, held below the top mark. Bare 不 knocks it off the scale; 不是很 pins it in the middle.
我不是同意他們的意見 ✗ → 我不是很同意他們的意見 ✓ (the hedge needs the degree word: 不是很, not 不是 alone before a verb)
這句話的意思不是清楚 ✗ → 這句話的意思不是很清楚 ✓ (don't put 不是 straight before a bare stative; raise it with 很 first)
我不是很學生 ✗ → 我不是學生 ✓ (before a bare noun 不是 is the plain copula negation; 很 does not belong there)
English 'not entirely / not really' maps onto 不是很, but learners reach for it by translating 'be' literally and stack 不是 before adjectives or bare nouns where Chinese either raises with 很 (不是很清楚) or drops 是 for the plain copula negation (不是學生).