late 14c., “relationship, relation; regard, consideration,” 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” are from 1580s, as is sense of “point, particular feature.”
1540s, “to regard,” from Middle French respecter “look back; respect; delay,” 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”).
Meaning “treat with deferential regard or esteem” is from 1550s. Sense of “refrain from injuring” is from 1620s. Meaning “have reference 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.
Excerpted from etymonline