c. 1200, from Old Norse geta (past tense gatum, past participle getenn) "to obtain, reach; to be able to; to beget; to learn; to be pleased with," a word of very broad meaning, often used almost as an auxilliary verb, also frequently in phrases (such as geta rett "to guess right"). This is from Proto-Germanic *getan (source also of Old Swedish gissa "to guess," literally "to try to get"), from PIE root *ghend- "to seize, take."
Old English, as well as Dutch and Frisian, had the verb almost exclusively in compounds (such as begietan, "to beget;" forgietan "to forget"). Vestiges of an Old English cognate *gietan remain obliquely in modern past participle gotten and original past tense gat, also Biblical begat.
In compound phrases with have and had it is grammatically redundant, but often usefully indicates possession, obligation, or necessity, or gives emphasis. The word and phrases built on it take up 29 columns in the OED 2nd edition; Century Dictionary lists seven distinct senses for to get up.
"I GOT on Horseback within ten Minutes after I received your Letter. When I GOT to Canterbury I GOT a Chaise for Town. But I GOT wet through before I GOT to Canterbury, and I HAVE GOT such a Cold as I shall not be able to GET rid of in a Hurry. I GOT to the Treasury about Noon, but first of all I GOT shaved and drest. I soon GOT into the Secret of GETTING a Memorial before the Board, but I could not GET an Answer then, however I GOT Intelligence from the Messenger that I should most likely GET one the next Morning. As soon as I GOT back to my Inn, I GOT my Supper, and GOT to Bed, it was not long before I GOT to Sleep. When I GOT up in the Morning, I GOT my Breakfast, and then GOT myself drest, that I might GET out in Time to GET an Answer to my Memorial. As soon as I GOT it, I GOT into the Chaise, and GOT to Canterbury by three: and about Tea Time, I GOT Home. I HAVE GOT No thing particular for you, and so Adieu." [Philip Withers, "Aristarchus, or the Principles of Composition," London, 1789, illustrating the widespread use of the verb in Modern English]
As a command to "go, be off" by 1864, American English. Meaning "to seize mentally, grasp" is from 1892. Get wind of "become acquainted with" is from 1840, from earlier to get wind "to get out, become known" (1722). To get drunk is from 1660s; to get religion is from 1772; to get better "recover health" is from 1776. To get ready "prepare oneself" is from 1890; to get going "begin, start doing something" is by 1869 in American English; get busy "go into action, begin operation" is from 1904. Get lost as a command to go away is by 1947. To get ahead "make progress" is from 1807. To get to (someone) "vex, fret, obsess" is by 1961, American English (get alone as "to puzzle, trouble, annoy" is by 1867, American English). To get out of hand originally (1765) meant "to advance beyond the need for guidance;" sense of "to break free, run wild" is from 1892, from horsemanship. To get on (someone's) nerves is attested by 1970.
word-forming element meaning "not, opposite of, without" (also im-, il-, ir- by assimilation of -n- with following consonant, a tendency which began in later Latin), from Latin in- "not," cognate with Greek an-, Old English un-, all from PIE root *ne- "not."
In Old French and Middle English often en-, but most of these forms have not survived in Modern English, and the few that do (enemy, for instance) no longer are felt as negative. The rule of thumb in English has been to use in- with obviously Latin elements, un- with native or nativized ones.
the adverb in attached to a verb as a word-forming element, by 1960, abstracted from sit-in, which is attested from 1941 in reference to protests and 1937 in reference to labor union actions (which probably was influenced by sit-down strike) but was popularized in reference to civil disobedience protests aimed at segregated lunch counters.
As a word-forming element it was extended first of other types of protests, then by 1965 to any sort of communal gathering (such as love-in, attested by 1967). In labor actions it was perhaps less useful: "a mass of workers calling in sick to absent themselves in protest" was called both a sick-out (1970) and a sick-in (1974).
word-forming element in chemistry, usually indicating a neutral substance, antibiotic, vitamin, or hormone; a modification and specialized use of -ine (2).
a Middle English merger of Old English in (prep.) "in, into, upon, on, at, among; about, during;" and Old English inne (adv.) "within, inside," from Proto-Germanic *in (source also of Old Frisian, Dutch, German, Gothic in, Old Norse i), from PIE root *en "in." The simpler form took on both senses in Middle English.
Sense distinction between in and on is from later Middle English, and nuances in use of in and at still distinguish British and American English (in school/at school). Sometimes in Middle English shortened to i.
The noun sense of "influence, access (to power or authorities)," as in have an in with, is first recorded 1929 in American English. to be in for it "certain to meet with something unpleasant" is from 1690s. To be in with "on friendly terms with" is from 1670s. Ins and outs "intricacies, complications of an action or course" is from 1660s. In-and-out (n.) "copulation" is attested from 1610s.
element meaning "into, in, on, upon" (also im-, il-, ir- by assimilation of -n- with following consonant), from Latin in- "in," from PIE root *en "in."
In Old French (and hence in Middle English) this often became en-, which in English had a strong tendency to revert to Latin in-, but not always, which accounts for pairs such as enquire/inquire. There was a native form, which in West Saxon usually appeared as on- (as in Old English onliehtan "to enlighten"), and some of those verbs survived into Middle English (such as inwrite "to inscribe"), but all now seem to be extinct.
Not related to in- (1) "not," which also was a common prefix in Latin, causing confusion: to the Romans impressus could mean "pressed" or "unpressed;" inaudire meant "to hear," but inauditus meant "unheard of;" in Late Latin investigabilis could mean "that may be searched into" or "that cannot be searched into." Latin invocatus was "uncalled, uninvited," but invocare was "to call, appeal to."
The trouble has continued in English; the hesitation over what is meant by inflammable being a commonly cited example. Implume (1610s) meant "to feather," but implumed (c. 1600) meant "unfeathered." Impliable can mean "capable of being implied" (1865) or "inflexible" (1734). Impartible in 17c. could mean "incapable of being divided" or "capable of being imparted." Impassionate can be "free from passion" or it can mean "strongly stirred by passion." Inanimate (adj.) is "lifeless," but Donne uses inanimate (v.) to mean "infuse with life or vigor." Irruption is "a breaking in," but irruptible is "unbreakable."
In addition to improve "use to one's profit," Middle English also had a verb improve meaning "to disprove" (15c.). To inculpate is "to accuse," but inculpable means "not culpable, free from blame." Infestive has meant "troublesome, annoying" (1560s, from infest) and "not festive" (1620s). In Middle English inflexible could mean "incapable of being bent" or "capable of being swayed or moved." In 17c., informed could mean "current in information," formed, animated," or "unformed, formless" ("This was an awkward use" [OED]). Inhabited has meant "dwelt in" (1560s) and "uninhabited" (1610s); inhabitable likewise has been used on opposite senses, a confusion that goes back to Late Latin.