ねずみ・鼠nezumi[0]heiban (flat)

1. nounmouse; rat
   猫ねこがいなくなるとネズミたちが遊あそびだす。↗

   When the cat is away, the mice will play.
2. noundark gray; slate gray

• SynonymマウスNeutralLoanword for mice — the smaller kind, most often in laboratory contexts; also means a computer mouse. Everyday use: 「ネズミ」.
• Synonym鼠ねずNeutralShortened form of 「ねずみ」, also used as a short form of the color 「鼠色」. For the animal in everyday speech, say 「ネズミ」.
• SynonymラットNeutralLoanword for rats — the larger kind, most often in laboratory contexts. In everyday speech, 「ネズミ」 is the usual word.

For the animal in everyday speech, 「ネズミ」 is the default. Use 「ラット」 for (lab) rats and 「マウス」 for (lab) mice or a computer mouse; 「ねず」 is an old-fashioned short form.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. ねずみ。