Strong's 5594 (ψύχω)

wax cold

to breathe (voluntarily but gently, thus differing on the one hand from G4154 (πνέω), which denotes properly a forcible respiration; and on the other from the base of G109 (ἀήρ), which refers properly to an inanimate breeze), i.e. (by implication, of reduction of temperature by evaporation) to chill (figuratively)

a primary verb;