late 14c., "a portion or part of something" (a sense preserved in the verb and in the phrase parcel of land, which is from c. 1400), from Old French parcele "small piece, particle, parcel," and directly from Medieval Latin parcella, from Vulgar Latin *particella, extended form (via a diminutive suffix, but not necessarily implying smallness) of Latin particula "small part, little bit," itself a diminutive of pars (genitive partis) "a part, piece, fraction" (from PIE root *pere- (2) "to grant, allot").
Meaning "a package" is recorded from 1640s from the earlier sense of "a quantity of goods in a package" (mid-15c.), which is from the late 14c. sense of "an amount or quantity of anything." The expression part and parcel (early 15c.) also preserves the older sense; both words mean the same, the multiplicity is for emphasis. In some old and technical senses, parcel is used as an adjective or adverb meaning "in part, partially, to some degree." Parcel post as a service to deliver packages (later a branch of the postal service) is by 1790.
"to divide into small portions," early 15c., parcelen (with out), from parcel (n.). Related: Parceled; parcelled; parceling; parcelling.
"explosive projectile," originally consisting of a hollow ball or shell filled with explosive material, 1580s, from French bombe, from Italian bomba, probably from Latin bombus "a deep, hollow noise; a buzzing or booming sound," from Greek bombos "deep and hollow sound," echoic. Thus probably so called for the sound it makes.
Originally of mortar shells, etc.; modern sense of "explosive device placed by hand or dropped from airplane" is from 1909. The meaning "old car" is from 1953. The meaning "success" is from 1954 (late 1990s slang the bomb "the best" probably is a fresh formation); opposite sense of "a failure" is from 1961. The bomb "the atomic bomb" is from 1945. Compare shell (n.).
"strong enough to resist the impact and explosive force of bombs or shells striking on the outside" [Century Dictionary], 1702, from bomb (n.) + proof (n.). As a noun, "underground structure strong enough to resist the impact and explosive force of bombs," 1755. In the U.S. Civil War it was a contemptuous term for men not exposed to the dangers of war.