late 14c., "relationship, relation; regard, consideration" (as in in respect to), from Old French respect and directly from Latin respectus "regard, a looking at," literally "act of looking back (or often) at one," noun use of past participle of respicere "look back at, regard, consider," from re- "back" (see re-) + specere "look at" (from PIE root *spek- "to observe").
Meanings "feeling of esteem excited by actions or attributes of someone or something; courteous or considerate treatment due to personal worth or power." From late 15c. as "an aspect of a thing, a relative property or quality," hence "point, detail, particular feature" (1580s). With all due respect as a polite phrase introducing deferential disagreement is attested by 1670s.
1540s, "to regard, notice with especial attention," from French respecter "look back; respect; delay" (16c.), from Latin respectere, frequentative of respicere "look back at, regard, consider," from re- "back" (see re-) + specere "look at" (from PIE root *spek- "to observe").
The meaning "treat with deferential esteem, regard with some degree of reverence" is from 1550s. The sense of "refrain from injuring or interfering with" is from 1620s. The meaning "have reference to, relate to" is from 1560s. Related: Respected; respecting.
To respect the person was "show undue bias toward (or against) based on regard for the outward circumstances of a person;" hence respecter of persons, usually with negative, from Acts x:34, in the 1611 translation.
mid-15c., "relative, having relation or reference to something" (a sense now obsolete), from Medieval Latin respectivus "having regard for," from Latin respect- past-participle stem of respicere "look back at, regard, consider" (see respect (v.)). The meaning "relating or pertaining severally each to each, connected with each of those in question" is from 1640s.
"expressions or signs of esteem, deference, or compliment," 1610s; see respect (n.). Earlier (late 14c.) as "aspects, particular respects." For "expression of regard," Middle English had respeccioun (respection), from Latin. To pay (one's) respects "show polite attention by visiting or making a call" is by 1660s.
Of persons, "having an honest reputation" from 1755; the sense of "moderately well-to-do and deserving respect for morality; occupying a fairly good position in society" is by 1800. From 1755 as "considerable in size or number;" from 1775 as "not too big, tolerable, fair, mediocre." Related: Respectably.