[nut] {n.} 1. Head. 2. Eccentric person.

[nut case] {n. phr.} A very silly, crazy, or foolish person. […]

[nutcase] {n.} An insane person.

[nuthouse] {n.} A lunatic asylum.

[nutmeg] {v.} In association football, to pass the ball between an […]

[nuts about] See: [CRAZY ABOUT].

[nuts and bolts of] {n. phr.} The basic facts or important […]

[nuts or nutty] {adj.} Crazy or insane.

[nutshell] See: [IN A NUTSHELL].

[nutter] {n.} Insane person.