Etymology
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mucus (n.)

"viscid fluid secreted by the mucous membranes of animals," 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 (source also of Latin emungere "to sneeze out, blow one's nose," mucere "be moldy or musty," Greek myssesthai "to blow the nose," myxa "mucus;" Sanskrit muncati "he releases"). Old English had horh, which may be imitative.

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mucous (adj.)

"containing or resembling slime or mucus," 1640s (replacing mucilaginous), from Latin mucosus "slimy, mucous," from mucus (see mucus). Related: mucosity.

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mucilage (n.)

late 14c., mussillage, "viscous substance found in vegetable material," from Old French mucilage (14c.) and directly from Late Latin mucilago "musty or moldy juice" (4c.), from Latin mucere "be musty or moldy," from mucus "mucus" (see mucus). Meaning "adhesive gum" is attested by 1859.

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muggy (adj.)

"damp and close, warm and humid," 1746, with -y (2) + obsolete mug "a fog, mist," from Middle English mugen "to drizzle" (of a fog or a mist, late 14c.), from a Scandinavian source such as Old Norse mugga "drizzling mist," which is possibly from PIE *meug- "slimy, slippery" (see mucus).

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moist (adj.)

late 14c., "slightly wet; well-irrigated, characterized by moistness," from Old French moiste "damp, wet, soaked" (13c., Modern French moite), which is of uncertain origin. Perhaps from Vulgar Latin *muscidus "moldy," also "wet," from Latin mucidus "slimy, moldy, musty," from mucus "slime" (see mucus). Alternative etymology [Diez] is from Latin musteus "fresh, green, new," literally "like new wine," from musteum "new wine" (see must (n.1)). If this wasn't the source, it influenced the form of the other word in Old French. Related: Moistly; moistness (mid-14c.).

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mold (n.2)

also mould, "minute, furry fungus," especially the types growing on neglected food and decaying organic matter, c. 1400, molde, probably from moulde, past participle of moulen "to grow moldy" (early 13c.), related to Old Norse mygla "grow moldy," possibly from Proto-Germanic *(s)muk- indicating "wetness, slipperiness," from PIE *meug- (see mucus). Or it might have evolved from (or been influenced by) Old English molde "loose earth" (see mold (n.3)).

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match (n.1)

"stick for striking fire." Late 14c., macche, "wick of a candle or lamp," a sense now obsolete, from Old French meiche "wick of a candle," from Vulgar Latin *micca/*miccia (source also of Catalan metxa, Spanish mecha, Italian miccia), which is of uncertain origin, probably ultimately from Latin myxa, from Greek myxa "lamp wick," originally "mucus," based on notion of wick dangling from the spout of a lamp like snot from a nostril, from PIE root *meug- "slimy, slippery" (see mucus). English snot also had a secondary sense from late 14c. of "snuff of a candle, burnt part of a wick," surviving at least to late 19c. in northern dialects.

The modern spelling is from mid-15c. The meaning "piece of cord or tow soaked in sulfur, used for lighting fires, lamps, candles, etc." is from 1530. It was used by 1830 for the modern type of sulfur-tipped wooden friction match, which were perfected about that time, and competed with lucifer for much of 19c. as the name for this invention. An earlier version consisted of a thin strip of wood tipped with combustible matter that required contact with phosphorous carried separately in a box or vial.

In the manufacture of matches much trouble has been occasioned by the use of phosphorous .... In some of the small and poorly-managed factories the men and children are never free from the fumes; their clothes and breath are luminous in the dark, and in the daytime white fumes may be seen escaping from them whenever they are seated by the fire. ... The danger arising from the use of matches was magnified, because they could sometimes be seen in the dark, were liable to ignite on a warm shelf, and were poisonous to such an extent that children had been killed by using them as playthings. [John A. Garver, "Matches," in The Popular Science Monthly, August 1877]
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smock (n.)
Old English smoc "garment worn by women, corresponding to the shirt on men," from Proto-Germanic *smukkaz (source also of Old Norse smokkr "a smock," but this is perhaps from Old English; Old High German smoccho "smock," a rare word; North Frisian smok "woman's shift," but this, too, perhaps from English).

Klein's sources, Barnhart and the OED see this as connected to a group of Germanic sm- words having to do with creeping or pressing close, such as Old Norse smjuga "to creep (through an opening), to put on (a garment)," smuga "narrow cleft to creep through; small hole;" Old Swedish smog "a round hole for the head;" Old English smugan, smeogan "to creep," smygel "a burrow." Compare also German schmiegen "to cling to, press close, nestle;" and Schmuck "jewelry, adornments," from schmucken "to adorn," literally "to dress up."

Watkins, however, traces it to a possible Germanic base *(s)muk- "wetness," figuratively "slipperiness," from PIE root*meug- "slimy, slippery" (see mucus). Either way, the original notion, then, seems generally to have been "garment one creeps or slips into," by the same pattern that produced sleeve and slip (n.2).

Now replaced by euphemistic shift (n.2); smock was the common word down to 18c., and was emblematic of womanhood generally, as in verb smock "to render (a man) effeminate or womanish" (1610s); smocker "man who consorts with women" (18c.); smock-face "person having a pale, effeminate face" (c. 1600). A smock-race (1707) was an old country pastime, a foot-race for women and girls with a smock as a prize. Modern meaning "woman's or child's loose dress or blouse" is from 1907; sense of "loose garment worn by artists over other clothes" is from 1938.
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pituitary (adj.)

1610s, "secreting or containing mucus," originally in reference to the small glands under the cerebrum, from Latin pituitarius "mucous," from pituita "clammy moisture, phlegm, mucus, slime," a word of unknown etymology. Taken as the name for the gland because it was believed that it channeled mucus to the nose. As a noun by 1899.

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booger (n.)
"nasal mucus," by 1890s; earlier bugger. Also boogie.
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