The Proto-Indo-European root *bʰeug-, *bʰeugʰ- "to bend". In Proto-Celtic it became *buggo- "soft, tender", then Scottish Gaelic bog "soft", borrowed into English as bog, which bends beneath the feet.
In Proto-Germanic the form *bʰeugʰ- became *ƀeuǥon. This gives us several words:
bow the noun "a bent or curved object" is from Old English boᵹa "bow".
bow the verb is from Old English strong verb būᵹan "to bend".
bagel is from Yiddish בייגל beygl, a diminutive formed from Old High German boug "ring".
buxom is from Middle English buhsum from Old English *(ge)būhsum from būgan. The word originally meant "obedient, compliant" in Old English, then "flexible, blithe" (which are now obsolete), then "plump, comely".