An octopus (a cephalopod marine animal), commonly eaten in dishes like sashimi or takoyaki.
今夜はたこ焼きパーティーをするから、たこを買ってきてください。
We're having a takoyaki party tonight, so please buy some octopus.
漁港で新鮮なたこがたくさん売られていた。
There were many fresh octopuses being sold at the fishing port.
たこの足は引き締まっていて、食感が良い。
Octopus legs are firm and have a pleasant texture.
Colloquially, a fool or idiot (informal/colloquial usage).
そんな簡単なこともできないなんて、たこだな。
You can't even do such a simple thing — what an idiot.
彼に騙されるなんて、自分がたこだと思った。
Being tricked by him made me feel like a fool.