"to fasten by or as if by a padlock," 1640s, from padlock (n.). Related: Padlocked; padlocking.
"removable lock with a pivoted bow or hasp," late 15c., pad-lok, from lock (n.1), but the first element is of obscure origin; perhaps originally, as some sources suggest, "a lock for a pannier."
"priest, chaplain," used in reference to priests in Spain, Italy, and Mexico and South America, or the southwest of the U.S., 1580s, from Italian, Spanish, or Portuguese padre, from Latin patrem (nominative pater) "father" (see father (n.)). The title of the regular clergy in those languages. Papar was the name the Norse arriving in Iceland gave to Irish monks whom they found there.
"hymn of praise, song of triumph;" in general use, "a loud and joyous song," 1590s, from Latin paean "hymn of deliverance, hymn to a help-giving god," from Greek paian "hymn, chant, hymn to Apollo," from Paian, Paiōn, a name of the god of healing; originally the physician of the gods (in Homer), later merged with Apollo; literally "one who touches" (i.e. "one who heals by a touch"), probably taken from a phrase or word at the beginning of the hymn, from paio "to touch, strike." The notion seems to be either a cry asking for aid in war or other trouble, or a giving thanks for aid received.