From the same as zugos; a couple, i.e. A team (of oxen yoked together) or brace (of birds tied together) -- yoke, pair.
see GREEK zugos
1. two draught-cattle (horses or oxen or mules) yoked together, a pair or yoke of beasts: Luke 14:19 (צֶמֶד, 1 Kings 19:19, etc.; often in Greek Writ; from Homer, Iliad 18, 543 down).
2. universally, a pair: Luke 2:24 (Herodotus 3, 130; Aeschylus Ag. 44; Xenophon, oec. 7, 18, and often in Greek writings).