TBESG:ψυχρόςcoldG:A ψυχρός, -ά, -όν (< ψύχω), [in LXX: Pro.25:25 (קַר), Refs Sir.43:20, 4Ma.11:26 * ;] cold: sc. ὕδωρ (cf. Theogn., 263; Hdt., ii, 37), Mat.10:42; metaph., of indifferent persons, Rev.3:15-16 † (AS)
Thayer:1) cold, cool 1a) of cool water 2) metaph. 2a) cold i.e. sluggish, inert 2b) in mind: of one destitute of warm Christian faith and the desire for holiness