Lewis & Short

ūmectātĭo (hūmec-), ōnis, f. [umecto], a moistening, watering, moisture: oris nauseabilis, Cael. Aur. Tard. 3, 2, 18: inimica (agri), Cassiod. Var. 10, 26.
Absol., Isid. 4, 7, 4; 20, 2, 16.