Mucilaginous, then, is an adjective that describes something oozy, slimy, and sticky. Some synonyms are albuminous, syrupy, and viscid — all good words.
You might think, as I did, that mucilaginous comes to us from the noun mucus, but that isn't exactly true. Both words come from the same root (the Latin mucus), but in English, the adjective form of mucus is mucous, which can be difficult to remember. Mucilaginous comes from the noun mucilage, which is a sticky, gummy substance that comes from some plants.
Think of it as plant snot.
Mucilage has been used in all sorts of glues and gums for around the house. (Mucus, not so much.)
So mucus (which is mucous) comes from animals, and mucilage (which is mucilaginous) comes from plants. Etymological acrobatics like that are nothing to sneeze at.
Pronunciation: The C in mucilage and mucilaginous is pronounced like an S, not like a K as it is in mucus and mucous.
From Edward Lear's "The Story of the Four Little Children Who Went Around the World" in Nonsense Songs, Stories, Botany, and Alphabets:
At this time, an elderly Fly said it was the hour for the evening-song to be sung; and, on a signal being given, all the Blue-Bottle-Flies began to buzz at once in a sumptuous and sonorous manner, the melodious and mucilaginous sounds echoing all over the waters, and resounding across the tumultuous tops of the transitory titmice upon the intervening and verdant mountains with a serene and sickly suavity only known to the truly virtuous.