- Gr. kunikós dog-like, currish, churlish, Cynic (the application being derived from the gymnasium (Κυνόσαργες) where they taught or from certain dog-like qualities), f. kun-, kúōn dog (HOUND)
So the word for the gymnasium, Kunósarges (Cynosarges), was applied to the philosophers who taught there. It seems that the name of the gymnasium comes from κύων ἀργός (kúōn argós) "white dog" (ἀργός from PIE *h₂erǵ- "to shine".) Alternatively, the Cynics were thought to have "certain dog-like qualities" - I'll let the AHD explain this.
Meanwhile *ḱwon- became *hunđaz "dog" in Proto-Germanic, then Old English hund and English hound.
Also related is corgi from Welsh cor "dwarf" and ci "dog". And the Celtic hero Cúchulainn, from Irish Gaelic cu Chulainn, "hound of Culann". And canary, from Latin canis "dog". Canaries are native to the Canary Islands, from Latin Canāriae Īnsulae, "islands of dogs".