ぬるい（ぬるい、nurui）
- lukewarm

The Japanese word ぬるい means "lukewarm," "tepid," or "not hot enough." It describes something that has a temperature between cold and hot, lacking significant warmth, and is often used to describe liquids. It can also imply something is lacking in enthusiasm or spirit. The core meaning focuses on the lack of a desired temperature, either by being insufficiently warm or just warm enough to be undesirable.

⚫︎お風呂のお湯がぬるい。 Translation: The bathwater is lukewarm. ⚫︎このコーヒーはぬるくて美味しくない。 Translation: This coffee is lukewarm and not delicious. ⚫︎彼の情熱はぬるい。 Translation: His passion is lukewarm.

You use ぬるい to describe the temperature of liquids (water, coffee, soup, etc.) or, figuratively, to describe a lack of intensity or enthusiasm. It's often used when something is not hot enough to be enjoyable or effective. It is important to note, ぬるい primarily refers to something being *warm*, not cold. It’s the absence of the desired degree of heat.

ぬるい is typically written in hiragana. The kanji form is 鈍い, but this represents a different word (dull) and has a distinct meaning. There are no variations in the okurigana, the suffix hiragana.

⚫︎生ぬるい (namanurui) - lukewarm (a bit more emphatic) ⚫︎生暖かい (nama-atatakai) - tepid; slightly warm ⚫︎温い (nurui) - Another form of ぬるい, this word is less common but means the same thing.

⚫︎熱い (atsui) - hot ⚫︎冷たい (tsumetai) - cold

このスープはぬるいから、温め直してください。 ・Translation: This soup is lukewarm, so please reheat it. ・Explanation: The speaker is requesting that the soup, which is currently not warm enough, be heated.

試合にぬるい態度で臨んではいけない。 ・Translation: You must not approach the match with a lukewarm attitude. ・Explanation: This sentence uses ぬるい figuratively, to describe a lack of enthusiasm or effort.

The etymology of ぬるい isn't definitively known, but it likely evolved from a combination of the root "nu-" (related to warmth or wetness) and "-rui," which is an adjective ending. It is related to the word 温い (nurui), which shares the same meaning and likely influenced its development. The connection is rooted in the absence of significant heat.