push: [from the operation that puts the current information on a stack,

:push: [from the operation that puts the current information on a
stack, and the fact that procedure return addresses are saved on a
stack] (Also PUSH /push/ or PUSHJ /push'J/, the latter based on
the PDP-10 procedure call instruction.) 1. To put something onto a
{stack} or {pdl}. If one says that something has been pushed
onto one's stack, it means that the Damoclean list of things
hanging over ones's head has grown longer and heavier yet. This
may also imply that one will deal with it *before* other
pending items; otherwise one might say that the thing was `added
to my queue'. 2. vi. To enter upon a digression, to save the
current discussion for later. Antonym of {pop}; see also
{stack}, {pdl}.
-- The AI Hackers Dictionary