Also see definition of "Cousin" in Word Study
Study Dictionary
Cousin
COUSIN [ISBE]
COUSIN - kuz'-'-n (anepsios): Only in Col 4:10, where Mark is said to be "cousin" (Revised Version) to Barnabas, and not as in the King James Version, "sister's son." The renderings "cousin" of the King James Version for suggenes, in Lk 1:36,58 were probably understood at the time of the translation, in the wider, and not in the more restricted, sense of the term, now almost universally prevalent. In view of this the renderings "kinswoman," "kinsfolk" in the Revised Version (British and American) are preferable. As a title of honor and dignity, it occurs in 1 Esdras 4:42, etc.See KINSMAN.
Also see definition of "Cousin" in Word Study