Refers to a painful, hardened area of skin on the foot, resembling a fish eye. Common in everyday health contexts.
I have a corn on the sole of my foot and it hurts.
Corns tend to form where pressure is applied.
Katakana spelling, sometimes used for clarity or emphasis.
Search-only kanji form; not a practical spelling.
From the resemblance of a corn's hard core to a fish's eye. The exact historical derivation is uncertain, but the term is widely used in modern Japanese.