Nanook of the North

From Memory Alpha, the free Star Trek reference.

Nanook of the North was a nickname given to Odo by Vic Fontaine, as a means of personifying Odo's personality, which was compared to an icicle, further stating "Cool is one thing, but you're frozen solid."

Upon learning Odo's affection for Kira Nerys, Vic attempted to lead Odo down a path that would let him thaw out a bit, so that Odo could allow his emotions come to the surface, so to win Nerys heart. (DS9: "His Way")

Vic's usage of the term Nanook of the North originates from the documentary film of the same name, which featured the life of an Inuit named 'Nanook' who lived in the Arctic of North America.