Origin and history of respond

1650s, in a Christian context, "a godparent, one who binds himself or herself at a child's baptism to guarantee a religious education," from Late Latin sponsor "sponsor in baptism," in classical Latin "a surety, guarantee, bondsman," from sponsus, past participle of spondere "give assurance, promise solemnly," from Proto-Italic *spondejo- "to pledge," literally "to libate many times," from PIE *spondeio- "to libate" (source also of Hittite ishpanti- "to bring a fluid sacrifice, pour;" Greek spendein "make a drink offering," spondē "libation, offering of wine;" compare spondee).

The general sense of "one who binds himself to answer for another and be responsible for his conduct" is by 1670s. The sense of "person who pays toward the cost of a radio (or, after 1947, television) broadcast" is recorded by 1931. Related: Sponsorial. From the same Latin verb come spouse, correspond, respond, despond.

1520s, "to be in agreement, to be in harmony with," from French correspondre (14c.) or directly from Medieval Latin correspondere "correspond, harmonize, reciprocate," from assimilated form of com "together, with (each other)" (see com-) + respondere "to answer" (see respond).

Originally in Medieval Latin of two things in mutual action, but by later Medieval Latin it could be used of one thing only. In English, sense of "to be similar" (to) is from 1640s; that of "to hold communication with" is from c. 1600; specifically "to communicate by means of letters" from 1640s (in mid-18c. it also could mean "have sex"). Related: Corresponded; corresponding.