"seed covering," Middle English hol, hole, from Old English hulu "husk, pod," from Proto-Germanic *hulu- "to cover" (source also of Old High German hulla, hulsa; German Hülle, Hülse, Dutch huls), from PIE root *kel- (1) "to cover, conceal, save." Figurative use by 1831.
"body of a ship," 1550s, usually said to be identical with hull (n.1) on fancied resemblance of ship keels to open peapods. Compare 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." The alternative etymology is from Middle English hoole "ship's keel" (mid-15c.), from the same source as hold (n.) and conformed to hull (n.1).
On, Upon. These words are in many uses identical in force, but upon is by origin (up + on) and in use more distinctly expressive of motion to the object from above or from the side. On has the same force, but is so widely used in other ways, and so often expresses mere rest, that it is felt by careful writers to be inadequate to the uses for which upon is preferred. [Century Dictionary, 1895]
"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."
"distinctive arrangement of sails, masts, etc. on a ship; the characteristic manner of fitting the masts and rigging to the hull of any vessel," without regard to the hull, 1822, from rig (v.). Extended to costume, clothing outfit, especially if of a fanciful description, by 1843. Extension to a horse-drawn vehicle (1831) led to the sense of "truck, bus, etc." (1851); and apparatus for well-sinking (1875).
"space in a ship below the lower deck, in which cargo is stowed," 15c. corruption of Middle English holl "hull of a ship, hold of a ship" (c.1400), which is probably from earlier Middle English nouns meaning either "hole, hollow place, compartment" (see hole (n.)) and "husk, pod, shell," (see hull (n.1)). With form altered in the direction of hold (probably by popular apprehension that it is named because it "holds" the cargo) and sense influenced by Middle Dutch hol "hold of a ship."