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, notice with especial attention," from 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, regard with some degree of reverence" is from 1550s. Sense of "refrain from injuring or interfering with" is from 1620s. 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.