trident

From Latin tridēns, a fusion of tri- ("three") and dēns ("tooth") — literally a three-toothed thing.

The word simply describes its own shape: three tooth-like prongs, a name so literal it never needed to shift meaning.

The -dēns part shares the same root sense as "tooth" in English, since dēns names the tooth directly; the number tri- traces back to the PIE word *tréyes, the ancestor of "three."