退屈な

boring: 「退屈(させるよう)な」という意の最も一般的な語で, とにかく面白くなく, 我慢できないほど退屈な状況をさす

dull: 〘主に書〙 で, 人を興奮させるような面白さがない様子を表す

tedious: 面白くない事が長時間続いて退屈なことをいう

not very interesting: 上の3語のような直接的な表現を避けて〘遠回しに〙 退屈な気持ちを表すときに用いる

source: Dull Fake GIF - Dull Fake Smile - Discover & Share GIFs

1. lacking interest or excitement:

｟主に書･けなして｠ 〈人･話などが〉 【人にとって】退屈な, おもしろくない, 単調な «for, to» (↔ interesting;〖it is ～ to do/doing〗 …することは退屈だ (!日常英語では代わりにboringが用いられることも多い)

e.g. your diet doesn't have to be dull and boring.

archaic (of a person) feeling bored and dispirited:

〈人･動作などが〉活力がない; はきはきしない

e.g. she said she wouldn't be dull and lonely.

2. lacking brightness, vividness, or sheen:

〖通例名詞の前で〗くすんだ, ぼんやりした〈色･光〉(↔ bright)

e.g. his face glowed in the dull lamplight

e.g. his black hair looked dull.

(of the weather) overcast; gloomy:

〈天候が〉どんよりした, 曇った(↔ sunny)

e.g. next morning dawned dull.

(of sound) not clear; muffled:

鈍い〈音〉(↔ sharp); さえない〈味など〉

e.g. a dull thud of hooves.

(of pain) indistinctly felt; not acute:

〖名詞の前で〗鈍い〈痛み〉(↔ sharp)

e.g. there was a dull pain in his lower jaw.

(of an edge or blade) blunt:

｟やや古｠ 〈刃物などが〉切れ味が悪い, なまくらの, 〈鉛筆などが〉先がとがっていない(↔ sharp)

e.g. a lot more people are cut with dull knives than with sharp ones.

(of activity) sluggish or slow-moving:

｟主に米｠ 〈市場などが〉活気のない, 振るわない(↔ brisk)

e.g. gold closed lower in dull trading.

3. (of a person) slow to understand; stupid:

｟やや古｠ 〈人が〉頭の鈍い, 物わかりの悪い(stupid)

e.g. the voice of a teacher talking to a rather dull child.

archaic (of a person's senses) not perceiving things distinctly; insensitive.

make or become dull or less intense:

〈痛み･感情など〉を鈍くする, 弱くする, 和らげる

e.g. with object : time dulls the memory

〈痛み･感情などが〉鈍くなる, 弱くなる, 和らぐ.

e.g. no object : Albert's eyes dulled a little.

British extremely dull.

cause to be less keenly felt; reduce the intensity or effectiveness of:

e.g. she'd have to find something to dull the edges of the pain.

dullish |ˈdəliSH| adjective

dully |ˈdəlˌlē| adverb

Old English dol‘stupid’, of Germanic origin; related to Dutch dol ‘crazy’ and German toll ‘mad, fantastic, wonderful’.