humdudgeon

The amis as words

Grantaire: Rhotacism - the excessive use of the letter R
Courfeyrac: Callipygian - having shapely buttocks
Jehan: Bardolatry - excessive admiration for Shakespeare
Combeferre: Cereology - the study of crop circles
Bossuet: Hoddy Hoddy - a foolish person
Joly: Humdudgeon - an imaginary illness
Bahorel: Boffola - a joke that gets a loud or hearty laugh
Feuilly: Incunabula - books printed before 1501
Enjolras: Logomachy - an argument about words
Also
Marius: Blatherskite - a person who talks at great length without making sense
Cosette: Ensorcell - to enchant or fascinate someone
Eponine: Coprocalia - the involuntary repetition of obscene language
Muichetta: Gallus - bold or daring