"manner of acting toward or before others," c. 1600, from French déportement, from déporter "to behave," from Old French deporter (see deport (v.1)).
"bearing, mien, carriage, demeanor, deportment," c. 1300, from Old French port "carriage demeanor," from porter "to carry," from Latin portare "to carry" (source of port (v.2)), from PIE root *per- (2) "to lead, pass over." From c. 1400 as "external appearance;" by 1520s in the now-archaic sense of "state, style, establishment."
late 15c., demenure, "conduct, management, treatment, behavior toward someone," from obsolete Middle English demean, demeinen "to handle, manage, conduct," later "behave in a certain way, conduct oneself" (early 14c.), from Old French demener (11c.) "to guide, conduct; to live, dwell," from de- "completely" (see de-) + mener "to lead, direct," from Latin minari "to threaten," in Late Latin "to drive (a herd of animals);" see menace (n.). Meaning "behavior, bearing, deportment" is from late 15c. Spelling changed by influence of nouns in -or, -our.
late 14c., obeisaunce, "act or fact of obeying, submissiveness, quality of being compliant or dutiful; respectful submission, homage," from Old French obeissance "obedience, service, feudal duty" (13c.), from obeissant, present participle of obeir "to obey," from Latin oboedire "to obey" (see obey). The sense in English altered late 14c. to "bending or prostration of the body as a gesture of submission or respect, a bow or curtsy; deferential deportment; an act of reverence or deference" by influence of abase. Related: Obeisant.
word-forming element meaning "a speaking, discourse, treatise, doctrine, theory, science," from Greek -logia (often via French -logie or Medieval Latin -logia), from -log-, combining form of legein "to speak, tell;" thus, "the character or deportment of one who speaks or treats of (a certain subject);" from PIE root *leg- (1) "to collect, gather," with derivatives meaning "to speak (to 'pick out words')." Often via Medieval Latin -logia, French -logie. In philology "love of learning; love of words or discourse," apology, doxology, analogy, trilogy, etc., Greek logos "word, speech, statement, discourse" is directly concerned.
c. 1500, "weight, dignity, seriousness, solemnity of deportment or character, importance," from Old French gravité "seriousness, thoughtfulness" (13c.) and directly from Latin gravitatem (nominative gravitas) "weight, heaviness, pressure," from gravis "heavy" (from PIE root *gwere- (1) "heavy"). The scientific sense of "downward acceleration of terrestrial bodies due to gravitation of the Earth" first recorded 1620s.
The words gravity and gravitation have been more or less confounded; but the most careful writers use gravitation for the attracting force, and gravity for the terrestrial phenomenon of weight or downward acceleration which has for its two components the gravitation and the centrifugal force. [Century Dictionary, 1902]
"excessive or monotonous use of distinctive methods in art or literature," 1803, from manner + -ism. Meaning "an instance of mannerism, habitual peculiarity in deportment, speech, or execution" is from 1819. Related: Mannerisms.
Perhaps few of those who write much escape from the temptation to trade on tricks of which they have learnt the effectiveness; & it is true that it is a delicate matter to discern where a peculiarity ceases to be an element in the individuality that readers associate pleasantly with the writer they like, & becomes a recurrent & looked-for & dreaded irritation. But at least it is well for every writer to realize that, for his as for other people's mannerisms, there is a point at which that transformation does take place. [Fowler]