n 1  :  a protective covering for the face  2 a  :  a device covering the mouth and nose to facilitate inhalation  b  :  a comparable device to prevent the broadcasting of exhaled infective material  3  :  a cosmetic preparation for the skin of the face that produces a tightening effect as it dries
vt 1  :  to prevent (an atom or group of atoms) from showing its ordinary reactions <to hydroxyl in a sugar by converting it into methoxyl>   2  :  to modify or reduce the effect or activity of (as a process or a reaction)  3  :  FLAVOR < a pharmaceutical preparation>   4  :  to raise the audibility threshold of (a sound) by the simultaneous presentation of another sound .
 
 
 
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