2nd nominative singular personal pronoun, Old English þu, from Proto-Germanic *thu (source also of Old Frisian thu, Middle Dutch and Middle Low German du, Old High German and German du, Old Norse þu, Gothic þu), from PIE *tu-, second person singular pronoun (source also of Latin tu, Irish tu, Welsh ti, Greek su, Lithuanian tu, Old Church Slavonic ty, Sanskrit twa-m).
Superseded in Middle English by plural form you (from a different root), but retained in certain dialects (e.g. early Quakers). The plural at first was used in addressing superior individuals, later also (to err on the side of propriety) strangers, and ultimately all equals. By c. 1450 the use of thou to address inferiors gave it a tinge of insult unless addressed by parents to children, or intimates to one another. Hence the verb meaning "to use 'thou' to a person" (mid-15c.).
Avaunt, caitiff, dost thou thou me! I am come of good kin, I tell thee!
["Hickscorner," c. 1530]
A brief history of the second person pronoun in English can be found here.
"to defecate," 1846, from a cluster of older nouns, now dialectal or obsolete, applied to things cast off or discarded (such as "weeds growing among corn" (early 15c.), "residue from renderings" (late 15c.), underworld slang for "money" (18c.), and in Shropshire, "dregs of beer or ale"), all probably from Middle English crappe "grain that was trodden underfoot in a barn, chaff" (mid-15c.), from French crape "siftings," from Old French crappe, from Medieval Latin crappa, crapinum "chaff." Related: Crapped; crapping.
For connection of the idea of defecation with that of shedding or casting off from the body, compare shit (v.). Despite the etymological legend, the word is not from the name of Thomas Crapper (1837-1910) who was, however, a busy plumber and may have had some minor role in the development of modern toilets. The name Crapper is a northern form of Cropper (attested from 1221), an occupational surname, obviously, but the exact reference is unclear. Crap (v.) as a variant of crop (v.) was noted early 19c, as a peculiarity of speech in Scotland and what was then the U.S. Southwest (Arkansas, etc.).
Draw out yere sword, thou vile South'ron!
Red wat wi' blude o' my kin!
That sword it crapped the bonniest flower
E'er lifted its head to the sun!
[Allan Cunningham (1784-1842), "The Young Maxwell"]
In English, the Ottoman sultan was the Grand Turk (late 15c.), and the Turk was used collectively for the Turkish people or for Ottoman power (late 15c.). From 14c. and especially 16c.-18c. Turk could mean "a Muslim," reflecting the Turkish political power's status in the Western mind as the Muslim nation par excellence. Hence Turkery "Islam" (1580s); turn Turk "convert to Islam."
Meaning "person of Irish descent" is first recorded 1914 in U.S., apparently originating among Irish-Americans; of unknown origin (Irish torc "boar, hog" has been suggested). Young Turk (1908) was a member of an early 20c. political group in the Ottoman Empire that sought rejuvenation of the Turkish nation. Turkish bath is attested from 1640s; Turkish delight from 1877.
"brother or sister," 1903, modern revival (in anthropology) of Old English sibling "relative, kinsman," from sibb "kinship, relationship; love, friendship, peace, happiness," from Proto-Germanic *sibja- "blood relation, relative," properly "one's own" (source also of Old Saxon sibba, Old Frisian, Middle Dutch sibbe, Old High German sippa, German Sippe, Gothic sibja "kin, kindred"), from PIE *s(w)e-bh(o)- (source also of Old Church Slavonic sobistvo, Russian sob "character, individuality"), an enlargement of the root *swe- "self" (see idiom). Related to the second element in gossip.
The word 'sib' or 'sibling' is coming into use in genetics in the English-speaking world, as an equivalent of the convenient German term 'Geschwister' [E.&C. Paul, "Human Heredity," 1930]
In Old English, sibb and its compounds covered grounds of "brotherly love, familial affection" which tended later to lump into love (n.), as in sibsumnes "peace, concord, brotherly love," sibbian (v.) "bring together, reconcile," sibbecoss "kiss of peace." Sibship, however, is a modern formation (1908). Sib persisted through Middle English as a noun, adjective, and verb expressing kinship and relationship.
"the mark in the middle of the belly where the umbilical cord was attached in the fetus," Middle English navele, from Old English nafela, nabula, from Proto-Germanic *nabalan (source also of Old Norse nafli, Danish and Swedish navle, Old Frisian navla, Middle Dutch and Dutch navel, Old High German nabalo, German Nabel), from PIE *(o)nobh- "navel" (source also of Sanskrit nabhila "navel, nave, relationship;" Avestan nafa "navel," naba-nazdishta "next of kin;" Persian naf; Latin umbilicus "navel;" Old Prussian nabis "navel;" Greek omphalos; Old Irish imbliu). For Romanic words, see umbilicus.
The cords of all link back, strandentwining cable of all flesh. [Joyce, "Ulysses"]
"Navel" words from other roots include Lithuanian bamba, Sanskrit bimba- (also "disk, sphere"), Greek bembix, literally "whirlpool." Old Church Slavonic papuku, Lithuanian pumpuras are originally "bud." Considered a feminine sexual center since ancient times, and still in parts of the Middle East, India, and Japan. In medieval Europe, it was averred that "[t]he seat of wantonness in women is the navel" [Cambridge bestiary, C.U.L. ii.4.26]. Words for it in most languages have a secondary sense of "center."
Meaning "center or hub of a country" is attested in English from late 14c. To contemplate (one's) navel "meditate" is from 1933; hence navel-gazer (by 1947); see also omphaloskepsis. Navel orange is attested from 1831.
Another great key I will give you is to be found by the contemplation of the Manipur Lotus, which is in the navel, or thereabouts. By contemplating this center you will be able to enter and go into another person's body, and to take possession of that person's mind, and to cause him to think and to do what you want him to do; you will obtain the power of transmuting metals, of healing the sick and afflicted, and of seership. ["Swami Brahmavidya," "Transcendent-Science or The Science of Self Knowledge," Chicago, 1922]