Why was "tantrum" trending last week?
1660s (replacing Middle English mucilage), from Latin mucus "slime, mold, mucus of the nose, snot," from PIE root *meug- "slippery, slimy," with derivatives referring to wet or slimy substances or conditions (cf. Latin emungere "to sneeze out, blow one's nose," mucere "be moldy or musty," Greek myssesthai "to blow the nose," myxa "mucus," mykes "fungus," Sanskrit muncati "he releases"). Old English had horh, which may be imitative.
mucus mu·cus (myōō'kəs)
The viscous slippery substance that consists chiefly of mucin, water, cells, and inorganic salts and that is secreted as a protective lubricant coating by the cells and glands of the mucous membranes.