spade

The digging tool comes from Middle English spade, from Old English spada, spadu, from Proto-Germanic *spadô. The card suit sense probably comes from Italian spade, plural of spada ("the ace of spades"), literally "sword," from Latin spatha, from Greek σπάθη (spáthē) — so named for the shape on the card, though exactly what that shape represented has been debated.

These are two separate words that happened to collide into one spelling: one an old Germanic tool-name, the other a borrowed card-suit term rooted in the idea of a sword or blade shape.

The tool sense is a doublet of spatha, spathe, and épée; the card sense is cognate with these too, since both ultimately trace back to Greek spáthē through different routes.