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to taper to a point; to become pointed; to become sharp
to be on edge; to be nervous; to be irritable; to be touchy
to be sharp (of a voice, words, etc.); to be harsh; to be angry; to look displeased; to look sour
to be provocative; to be radical; to be rebellious
鉛筆の先が尖っていて危ないので注意だ。
The pencil tip is sharp and dangerous.
神経が尖っているので休んだ方がいい。
Your nerves are on edge, so you should rest.
長年使った鉛筆の先が尖った。
The tip of the pencil I sharpened over the years became pointed.