"seed covering," from Old English hulu "husk, pod," from Proto-Germanic *hulus "to cover" (cf. Old High German hulla, hulsa; German Hülle, Hülse, Dutch huls). Figurative use by 1831.
"body of a ship," 1550s, perhaps from hull (n.1) on fancied resemblance of ship keels to open peapods (cf. Latin carina "keel of a ship," originally "shell of a nut;" Greek phaselus "light passenger ship, yacht," literally "bean pod;" French coque "hull of a ship; shell of a walnut or egg"). Alternative etymology is from Middle English hoole "ship's keel" (mid-15c.), from the same source as hold (n.).
"to remove the husk of," early 15c., from hull (n.1). Related: Hulled, which can mean both "having a particular kind of hull" and "stripped of the hull."