Etymology
Advertisement
go for (v.)
1550s, "be taken or regarded as," also "be in favor of," from go (v.) + for (adv.). Meaning "attack, assail" is from 1880. Go for broke is from 1951, American English colloquial.
Related entries & more 
Advertisement
tit for tat 
1550s, possibly an alteration of tip for tap "blow for blow," from tip (v.3) "tap" + tap "touch lightly." Perhaps influenced by tit (n.2).
Related entries & more 
main line (n.)

"principal line of a railway," 1841, from main (adj.) + line (n.). Meaning "affluent area of residence" is by 1917, originally (with capitals) that west of Philadelphia, from the "main line" of the Pennsylvania Railroad which added local stops to a string of backwater towns west of the city late 19c. that helped turn them into fashionable suburbs.

The Main Line, Philadelphia's most famous suburban district, was deliberately conceived in the 1870's and 1880's by the [Pennsylvania] Railroad, which built high-toned housing developments, ran hotels, more or less forced its executives to plunk their estates out there, and created a whole series of somewhat spurious Welsh towns along the railroad tracks. ... Now everybody assumes these all date from 1682, like the Robertses; but as Chestnut Hill people like to say, "nobody but Welsh peasants lived on the Main Line till the Railroad built it up." [Nathaniel Burt, "The Perennial Philadelphians," 1963]

The original station stops were, in order out from the city, Overbrook, Merion, Narberth, Wynnewood, Ardmore, Haverford, Bryn Mawr, Paoli. The train line for commuters along it is the Paoli Local.

Related entries & more 
pro bono 

short for Medieval Latin pro bono publico "for the public good;" from pro (prep.) "on behalf of, for" (see pro-) + ablative of bonum "good" (see bene-).

Related entries & more 
raison d'etre (n.)

"excuse for being," 1864, first recorded in letter of J.S. Mill, from French raison d'être, literally "rational grounds for existence."

Related entries & more 
Advertisement
g spot (n.)
also g-spot, 1981, short for Gräfenberg spot, named for German gynecologist Ernst Gräfenberg (1881-1957), who described it in 1950.
Related entries & more 
a deux 
French, à deux, literally "for two," from à, from Latin ad "to, toward; for" (see ad-) + deux (see deuce). By 1876 as a French term in English.
Related entries & more 
quid pro quo 

"one thing in place of another," 1560s, from Latin, literally "something for something, one thing for another," from nominative (quid) and ablative (quo) neuter singulars of relative pronoun qui "who" (from PIE root *kwo-, stem of relative and interrogative pronouns) + pro "for" (see pro-).

Related entries & more 
pro tempore 

"temporary," Latin, literally "for the time (being)," from pro "for" (see pro-) + ablative singular of tempus "time" (see temporal). Abbreviated form pro tem is attested by 1828.

Related entries & more 
T and A (n.)
1972, short for tits and ass (a phrase attributed to Lenny Bruce), in reference to salacious U.S. mass media; earlier it was medical shorthand for "tonsils and adenoids" (1942).
Related entries & more