Middle English rather, from Old English hraþor "more quickly; earlier, sooner," also "more readily or willingly," comparative of rathe (Old English hraþe, hræþe) "immediately, quickly, hastily, speedily; promptly, before long; readily," which is related to hræð "quick, nimble, prompt, ready," from Proto-Germanic *khratha- (source also of Old Norse hraðr, Old High German hrad), which is said to be from PIE *kret- "to shake."
The rather lambes bene starved with cold
[Spenser, "The Shepheardes Calender" (Februarie), 1579]
Meaning "on the contrary, in contrast to what just has been said" is from late 13c.; that of "more properly, more truly" is recorded from late 14c. Meaning "preferably" is from c. 1300. Sense of "to some extent, in a greater degree" is from 1590s, that of "somewhat, moderately" is by 1660s.
The adverb rathe was obsolete by 18c. except in poetry (Tennyson); the superlative rathest "earliest, soonest, first" fell from use by 17c. Middle English formed an alternative superlative ratherest (c. 1400) and also had rathely "quickly, swiftly; immediately" (early 14c.) and a noun rather "the former (persons)."
1650s, "exposition of principles," from Late Latin rationale, noun use of neuter of Latin rationalis "of reason" (see rational). Hence, "fundamental reason, the rational basis or motive of anything" (1680s).
"of a second class or group," 1660s, originally of ships, "of the second rate as to size, strength, etc.;" see rate (n.). Related: Second-rater.
1825, "a rendering rational, act of subjection to rational tests or principles," from rationalize + -ation. The specific sense in psychology in reference to subconscious means to justify behavior to make it seem rational or socially acceptable is by 1908.
Of the three works now on our table, the two which we have placed first have these laudable objects in view; an improvement on the former versions of the Psalms as compositions, and the rationalization, if we may so speak, of our Church psalmody. [The British Critic, London, Jan.-June 1825]
"restriction to limited allotments," 1865, verbal noun from ration (v.). Specifically of restrictions during wartime from 1917, in reference to conditions in England during the late stages of World War I.
"rebellious," by 1943, British nautical slang, perhaps a slang mangling of obstreperous. "Sea Passages: A Naval Anthology and Introduction to the Study of English" [1943, Geoffrey Callender] quotes from a letter:
Why Nobby should reckon that his raggie should blow the gaff, when there are crushers everywhere, leaves me guessing; but there it is. In the last dog he rounded on me and called me a white rat. I got stroppy and told him he was shooting a line: but all he said was, 'Oh! choke your luff! I'm looking for another oppo you snivelling sand-catcher.' So that looks like paying off.
to which Callender adds, "There is nothing in this letter which an active service rating could fail to understand."
Smelling salts (1840), used to revive the woozy, typically were a scented preparation of carbonate of ammonia. Smell-feast (n.) "one who finds and frequents good tables, one who scents out where free food is to be had" is from 1510s ("very common" c. 1540-1700, OED). Smell-smock "licentious man" was in use c. 1550-c. 1900. To smell a rat "be suspicious" is from 1540s.
"counsel, advice," Old English ræd "advice, counsel," from Proto-Germanic *redin (source also of Old Saxon rad "advice, counsel, help, advantage," Old Frisian red "council, advice," Dutch raad "advice, counsel," German Rat "advice, counsel," Old Norse rað "advice, consideration, remedy, power; marriage"), from the source of read (v.), which originally meant "to advise, counsel." A very frequent word in Old English and early Middle English, falling from literary use 17c. until revived somewhat in 19th century archaic and poetic diction.
The verb read in the already obsolete sense ' counsel, advise,' was much affected by Spenser, and in the early modern and ME. spelling rede which he used has likewise been much affected by his archaizing imitators; but there is no historical ground for a difference in spelling. [Century Dictionary]