Translation guide
Describes a person or thing that is unpredictable, moody, or prone to sudden changes in behavior or performance. The most common Japanese expressions focus on moodiness and unpredictability.
Describing a person whose mood changes quickly and often without warning.
A common, slightly casual noun for someone who is moody or acts on whims. Often used in everyday conversation.
He's temperamental, so he might suddenly get angry.
Literally 'has uneven moods.' A natural way to describe someone whose mood fluctuates. Can be used in both casual and polite speech.
She's temperamental and it's tiring to be around her.
Means 'emotional' and often implies being easily swayed by feelings, which can overlap with 'temperamental.' Slightly more formal than 気分屋.
Don't get temperamental; let's discuss this calmly.
Means 'easily changes one's mind' or 'fickle.' Emphasizes unpredictability in decisions or mood.
He's temperamental, so he sometimes forgets promises.
Describing a device, system, or performance that does not work consistently.
Means 'unstable' and is the most common word for temperamental machines or systems. Used in technical and everyday contexts.
This software is temperamental and crashes often.
Literally 'in bad condition.' A very common, casual way to say something is acting up or not working properly.
More technical, meaning 'operation is unstable.' Used for machinery or software.
Describing a person who gets angry quickly and unpredictably.
Means 'short-tempered' or 'quick to anger.' A common adjective/noun for someone with a short fuse.
He's temperamental and gets angry over little things.
Means 'prone to anger' or 'irritable.' Describes a personality trait.
気分屋 focuses on mood swings and whims, while 短気 specifically means quick to anger. A 気分屋 may not necessarily be angry, just unpredictable in mood. 短気 always implies a tendency to get angry quickly.
There is no single Japanese word that covers all meanings of 'temperamental.' Translating directly as 気質的 (きしつてき) is unnatural and rarely used. Choose the expression that matches the specific nuance.
The air conditioner is temperamental; it sometimes stops suddenly.
This printer is temperamental; it stops printing halfway.
Maybe because I'm tired lately, I've become temperamental.
Means 'hard to please' or 'cranky.' Often used for someone who is moody and easily annoyed.
That boss is temperamental; I have to be careful not to upset him.