c. 1400, pouerful, "mighty, having great strength or power," from power (n.) + -ful. Sense of "capable of exerting great force or power" is from 1580s.

Meaning "of great quality or number" is from 1811; hence the colloquial sense of "exceedingly, extremely" (adv.) is from 1822. Thornton ("American Glossary") notes powerful, along with monstrous,  as "Much used by common people in the sense of very," and cites curious expressions such as devilish good, monstrous pretty (1799), dreadful polite, cruel pretty, abominable fine (1803), "or when a young lady admires a lap dog for being so vastly small and declares him prodigious handsome" (1799).

This gross perversion is common in several of the Western counties of Pennsylvania, to which region I had supposed it was limited. A gentleman informs me, however that it is not unfrequent in the South, and that he has even heard it yoked with weak, as, A powerful weak man. [Seth T. Hurd, "A Grammatical Corrector; or, Vocabulary of the Common Errors of Speech," 1847]

Related: Powerfully; powerfulness.

1550s, "an abnormality of growth," from Late Latin monstrositas "strangeness," from Latin monstrosus, a collateral form of monstruosus (source of French monstruosité), from monstrum "divine omen, portent, sign; abnormal shape; monster, monstrosity," figuratively "repulsive character, object of dread, awful deed, abomination," from root of monere "to admonish, warn, advise," from PIE *moneie-"to make think of, remind," suffixed (causative) form of root *men- (1) "to think."

Earlier form was monstruosity (c. 1400). Sense of "state or quality of being monstrous" is first recorded 1650s. Meaning "a monster" is attested from 1640s.

late 14c., "objection, opposition; hostility, mutual opposition," also "absolute inconsistency," from Old French contradiction or directly from Late Latin contradictionem (nominative contradictio) "a reply, objection, counterargument," noun of action from past-participle stem of contradicere, in classical Latin contra dicere "to speak against, oppose in speech or opinion," from contra "against" (see contra) + dicere "to say, speak" (from PIE root *deik- "to show," also "pronounce solemnly"). Old English used wicwedennis as a loan-translation of Latin contradictio.

Meaning "an assertion of the direct opposite of what has been said or affirmed" is from c. 1400. Sense of "a contradictory fact or condition" is from 1610s.  Contradiction in terms "self-contradictory phrase" is attested from 1705. 

[C]ontradictions become elegance and propriety of language, for a thing may be excessively moderate, vastly little, monstrous pretty, wondrous common, prodigious natural, or devilish godly .... [Abraham Tucker, "The Light of Nature Pursued," 1805]

c. 1300, "fabulous man-like creature of enormous size," from Old French geant, earlier jaiant "giant, ogre" (12c.), from Vulgar Latin *gagantem (nominative gagas), from Latin gigas "a giant," from Greek Gigas (usually in plural, Gigantes), one of a race of divine but savage and monstrous beings (personifying destructive natural forces), sons of Gaia and Uranus, eventually destroyed by the gods. The word is of unknown origin, probably from a pre-Greek language. Derivation from gegenes "earth-born" is considered untenable.

In þat tyme wer here non hauntes Of no men bot of geauntes. [Wace's Chronicle, c. 1330]

It replaced Old English ent, eoten, also gigant (from Latin). The Greek word was used in Septuagint to refer to men of great size and strength, hence the expanded use in modern languages; in English of very tall and unusually large persons from 1550s; of persons who have any quality in extraordinary degree from 1530s. As a class of stars, from 1912. As an adjective from early 15c. Giant-killer is from 1726.

mid-14c., "large;" early 15c., "thick," also "coarse, plain, simple," from Old French gros "big, thick, fat; tall; strong, powerful; pregnant; coarse, rude, awkward; ominous, important; arrogant" (11c.), from Late Latin grossus "thick, coarse" (of food or mind), in Medieval Latin "great, big" (source also of Spanish grueso, Italian grosso), a word of obscure origin, not in classical Latin. It is said to be unrelated to Latin crassus, which meant the same thing, or to German gross "large," but said by Klein to be cognate with Old Irish bres, Middle Irish bras "big."

Its meaning forked in English. Via the notion of "coarse in texture or quality" came the senses "not sensitive, dull stupid" (1520s), "vulgar, coarse in a moral sense" (1530s). Via the notion of "general, not in detail" came the sense of "entire, total, whole, without deductions" (early 15c.), as in gross national product (1947). The meaning "glaring, flagrant, monstrous" is from 1580s; modern meaning "disgusting" is first recorded 1958 in U.S. student slang, from earlier use as an intensifier of unpleasant things (gross stupidity, etc.).

"pertaining to atoms," 1670s as a philosophical term (see atomistic); scientific sense dates from 1811, from atom + -ic. Atomic number is attested from 1821; atomic mass is from 1848.

Atomic energy is recorded by 1906 in the modern sense (as intra-atomic energy from 1903).

March, 1903, was an historic date for chemistry. It is, also, as we shall show, a date to which, in all probability, the men of the future will often refer as the veritable beginning of the larger powers and energies that they will control. It was in March, 1903, that Curie and Laborde announced the heat-emitting power of radium. [Robert Kennedy Duncan, "The New Knowledge," 1906]

Atomic bomb is first recorded 1914 in writings of H.G. Wells ("The World Set Free"), who thought of it as a bomb "that would continue to explode indefinitely."

When you can drop just one atomic bomb and wipe out Paris or Berlin, war will have become monstrous and impossible. [S. Strunsky, Yale Review, January 1917]

Atomic Age is from 1945. Atomic clock is from 1938. Atomical "concerned with atoms," also "very minute," is from 1640s.