gel

noun

1. (countable, uncountable)A semi-solid to almost solid colloid of a solid and a liquid, such as jelly, cheese or opal.

   “Similar studies of rats have employed four different intracranial resorbable, slow sustained release systems—surgical foam, a thermal gel depot, a microcapsule or biodegradable polymer beads.”

   “Researchers have developed a new gel they say is as durable as metal, has the flexibility of jello, and could revolutionize how our bodies heal and age.”

2. (countable, uncountable)Any gel intended for a particular cosmetic use, such as for styling the hair.
3. (countable, uncountable)A film of flexible transparent plastic (such as acetate, celluloid, or cellophane) suitable for making superimpositions or diapositives (image to overlay on other images, especially for overhead projectors); a digital virtual equivalent of this.
4. (British, slang)A girl.

   “"Now pray don't be troublesome, my dear gel," said Uncle Andrew.”

verb

1. (transitive)To apply (cosmetic) gel to (the hair, etc).

   “It ended, as it so often does, with that familiar smile. Cristiano Ronaldo – gelled hair, dazzling teeth, magic in his boots – will never forget the night he scored the 600th goal of an almost implausible career.”

2. (intransitive)To become a gel: to set up.
3. (intransitive)To develop a rapport.

   “He was a nice guy, and I got on OK with his friends, but the two of us never really gelled.”

4. (figuratively, intransitive)To come together to form something; to cohere.

   “We put our ideas together and they eventually gelled into a saleable product.”