interjection
Hesitation sound used when thinking, pausing, or showing mild doubt. Similar to English 'um' or 'well'.
See also: うん
ううん、ちょっと考えさせて。
Um, let me think for a moment.
うーん、どっちがいいかな。
Hmm, which one is better?
interjection
nuh-uh; no
Only with reading ううん
Casual negative reply, often with a falling intonation. Used to deny or refuse something informally. The reading is restricted to ううん; the long-vowel spelling うーん is not typical for this sense.
「もう食べた？」「ううん、まだ。」
"Did you eat already?" "Nope, not yet."
interjection
Sound made when straining, lifting something heavy, or feeling sudden pain. Similar to English 'oof' or a grunt.
See also: うん
うーん、この箱重い！
Oof, this box is heavy!
Long-vowel-marked spelling often used for the hesitation or groaning sense; less common for the negative reply.
Katakana spelling occasionally seen in manga or casual writing for the hesitation or groaning sense.
うん is an affirmative casual reply ('yeah'), while ううん (sense 2) is a negative casual reply ('nuh-uh'). The intonation and vowel length distinguish them.
A natural vocal hesitation or exclamation; the exact origin is uncertain. The negative sense likely developed from a nasalized, lengthened variant of the affirmative うん.