lay down v.
1. in senses of giving up [boxing imagery].
(a) [late 19C+] (US, also lay to, lie down) to volunteer for defeat; thus lay-down artist, a defeatist.
(b) [1910s+] to collapse.
(c) [1930s+] to accept, to acquiesce.
2. [1930s–60s] (drugs, also lay, lie down) to smoke opium [the smoker’s recumbent position].
3. [1930s+] (US prison) to place an inmate in the punishment cells [punishment cells were so cramped there was barely enough room to stand upright].
4. [1940s+] (US) to explain, to outline, to present a theory.
5. [1950s] (Aus. Und.) to retract a confession or witness statement.
[1930s+] (US drugs) a place to smoke opium.
[late 19C+] (US) to abandon someone, to fail in a duty.
SE in slang uses
[mid-19C–1930s] to die.
to act lazily; to do a job badly.
see under cow n.1
1. [1930s–40s] (US) to die [one ‘lays down’ one’s body].
2. [1940s+] (US) to drive very fast [the pressing down of the accelerator].