Translation guide
Describes something that is only slightly warm, often unpleasantly so. In Japanese, the most common word is ぬるい, but there are nuanced alternatives for liquids, weather, and figurative uses.
Describing water, tea, soup, or a bath that is not hot enough and feels lukewarm or unpleasantly cool.
The standard adjective for tepid liquids or baths. Often carries a negative nuance of being not hot enough.
This tea is tepid.
The bath has gone tepid.
Emphasizes an unpleasant lukewarmness, often used for drinks or weather. Stronger negative nuance than ぬるい.
Lukewarm beer is gross.
Specifically refers to tepid water, often used for bathing or washing. Can be neutral or slightly negative depending on context.
I wash my face with tepid water.
Describing air temperature that is mildly warm but not refreshing, often with a hint of stuffiness.
Used for air or wind that is unpleasantly warm, often in a humid or stuffy way. Common in describing weather.
A tepid wind is blowing tonight.
Can also describe air, but less common than 生暖かい for weather. Often implies a lack of freshness.
Describing a response, effort, or attitude that lacks enthusiasm or commitment; not fully engaged.
Pre-noun adjectival meaning half-hearted, superficial, or half-baked. Often used with 態度 (attitude) or 知識 (knowledge).
You can't succeed with a half-hearted attitude.
Means half-done, incomplete, or wishy-washy. Can describe efforts, responses, or states that are neither one thing nor the other.
His reply was tepid.
In slang or casual speech, ぬるい can describe a weak or unimpressive effort, similar to 'lame' or 'weak'.
ぬるい is specifically lukewarm and often negative. 温い (ぬくい in some dialects) can mean pleasantly warm, but standard Japanese uses あたたかい for pleasant warmth. 熱い means hot. Use ぬるい when something should be hot but isn't.
The soup is tepid (and should be hotter).
The soup is warm (pleasantly).
Avoid directly translating 'tepid' as ぬるい for non-liquid contexts like weather or attitudes without checking naturalness. For weather, 生暖かい is better; for attitudes, use 生半可 or 中途半端.
The air in the room is tepid.
That excuse is weak (tepid).