- slay (v.)
- Old English slean "to smite," also "to kill with a weapon" (class VI strong verb; past tense sloh, slog, past participle slagen), from Proto-Germanic *slakhanan, from root *slog- "to hit" (cf. Old Norse and Old Frisian sla, Danish slaa, Middle Dutch slaen, Dutch slaan, Old High German slahan, German schlagen, Gothic slahan "to strike").
The Germanic words are from PIE root *slak- "to strike" (cf. Middle Irish past participle slactha "struck," slacc "sword"). Modern German cognate schlagen maintains the original sense of "to strike." Meaning "overwhelm with delight" (mid-14c.) preserves some of the wider range of meanings that the word once had, including also "to strike a spark" (Old English).