shelf

Shelf comes from Middle English schelfe, probably from Old English sċylfe or sċilfe, meaning 'shelf, ledge, or deck of a ship.' That traces back through Proto-West Germanic *skilfijā and Proto-Germanic *skelfō to the Proto-Indo-European root *(s)kelH-, meaning 'to cut.'

The word narrowed over time from a broader sense of ledge, cliff, or ship's deck down to the flat board we picture today.

It's distantly related to sculpt and carve, and to shell, all tracing back to the same PIE root meaning 'to cut.' Cognates include Dutch schelf ('hay loft, haystack'), German Low German Schelf, and Old Norse skjalf ('bench').