雷 (kaminari) means “thunder” | MotiTan Japanese Dictionary

More examples

雷が鳴っています。kaminari ga na tte i ma su

Thunder is rumbling.

雷の音で、犬が驚いています。kaminari no oto de inu ga odoro i te i ma su

The dog is startled by the sound of thunder.

Covers the bright electrical flash and the loud rumble that occur during a storm.

雷鳴raimei: The loud rumbling sound produced by a storm.
稲光inabikari: The sudden bright flash that appears in the sky during a storm.

空中の放電によって生じる稲妻と雷鳴を一括していう語。kū chū no hō den ni yo tte shō ji ru inazuma to rai mei o ik katsu shi te i u go

雷 (kaminari) is a native Japanese word traditionally explained as 神 (kami, "god") combined with 鳴り (nari, "sound"), or the sound of a god.

In English, thunder refers to the sound and lightning to the flash, but Japanese 雷 (kaminari) may describe the storm phenomenon as a whole.