1. [mid-19C+] courage.
2. [late 19C+] (orig. US, also peck) the penis; a generic term for sex.
3. [1940s–80s] a general term of abuse.
4. [1980s] (US/Can.) a young child.
5. see peckerhead
[1980s] a health check, looking for symptoms of VD.
[1990s+] (US) smegma.
[1940s+] (US) an objectionable, aggressive person; also attrib.
[2000s] (US prison) a room set aside for conjugal visits.
[1990s+] (US) semen.
[1950s+] (US) semen left on a sheet or other similar object after intercourse or, usu., masturbation.
see under dead adj.
[mid-19C+] to stay cheerful, despite possible adversity; often as imp. keep your pecker up!
[1990s+] (US) to interfere; to become involved.