Slime was a gelatinous substance associated with many lifeforms, such as the Mellanoid slime worm and the Denebian slime devil. (TOS: "The Trouble with Tribbles"; TNG: "Coming of Age") Slime may be referred to in the vernacular as "goo". (TNG: "All Good Things...")
Life on Earth first arose from amino acids within, as Q put it, a "little pond of goo". (TNG: "All Good Things...")
Keenser's goo corroding a lock
In 2263 of the alternate reality, Keenser began excreting a very acidic green goo when he sneezed, making Chief Engineer Montgomery Scott paranoid that some of it might land on the USS Enterprise's warp core and destroy the ship. Later, when the crew was imprisoned at Krall's base on Altamid, Keenzer deliberately sneezed some goo on the lock of their cell door, allowing an escape attempt. (Star Trek Beyond)
A deleted scene also shows Keenser sneezing on his own uniform shirt at Starbase Yorktown, causing James T. Kirk to look down at his own shirt to see if any had gotten on him.
Spider cows had oral slime that contained a cure for the rage virus that infected the crew of the USS Cerritos in 2380. (LD: "Second Contact")
In 2381, Ensign Casey remarked dismissively to Brad Boimler that his friends Beckett Mariner, D'Vana Tendi, and Sam Rutherford, at the time engaged in anomaly consolidation duty, were "always elbow-deep in some kind of slime." Annoyed, Boimler replied, "Yeah, we work in Starfleet. I mean, slime's a given." (LD: "The Spy Humongous")