"pail or open vessel for drawing and carrying water and other liquids," mid-13c., from Anglo-French buquet "bucket, pail," from Old French buquet "bucket," which is from Frankish or some other Germanic source, or a diminutive of cognate Old English buc "pitcher, bulging vessel," originally "belly" (buckets were formerly of leather as well as wood), both from West Germanic *buh- (source also of Dutch buik, Old High German buh, German Bauch "belly"), possibly from a variant of PIE root *beu-, *bheu- "to grow, swell" (see bull (n.2)).
To kick the bucket "die" (1785) perhaps is from an unrelated bucket "beam on which something may be hung or carried" (1570s), from French buquet "balance," a beam from which slaughtered animals were hung (by the heels or hooves). This was perhaps reinforced by the notion of suicide by hanging after standing on an upturned bucket; but Farmer calls attention to bucket "a Norfolk term for a pulley." Bucket list "list of experiences or achievements one hopes to have or accomplish during one's remaining life," is by 2007, probably based on kicking the bucket as "dying," but the phrase was used earlier in algorithm sorting.