Green’s Dictionary of Slang

solid adj.

[SE solid, thorough, downright, vigorous; note Mezzrow & Wolfe, Really the Blues (1946): ‘Solid, which is short for solid as the Rock of Gibraltar and describes a man who isn’t going to be washed away so easy’]

1. [mid-19C+] full, complete, entire, esp. of time, e.g. a solid month.

2. [late 19C+] trusted; usu. as solid with.

3. [late 19C+] (orig. jazz) trustworthy, dependable, exciting, outstanding.

4. [late 19C-1900s] as solid on, solid for, devoted to.

5. [late 19C+] definite.

6. [late 19C-1950s] (US) secure, free of problems.

7. [1940s–60s] (Aus./N.Z.) severe, difficult, unfair, unreasonable.

In compounds

solid man (n.)

[late 19C] (US Und.) a woman’s long-term male lover (as opposed to any transient entanglements).

solid sender (n.) [send v.] [1920s+] (US black)

1. an admirable person, esp. a jazz or swing musician.

2. a real, genuine, amazing thing.

SE in slang uses

In compounds

solid ivory (adj.) [ivory n.]

[1910s–30s] (US) stupid; also as n., a stupid person.

solid shot (n.)

[late 19C] (US short order) an apple dumpling.