Literally: allowing another first choice
as to the use of some particular part of spacetime
, as when one stands aside to let someone jump a queue
, or stops one's vehicle
to let another's pass.
Metaphorically: the same in conceptual space.
In both cases, practically speaking, this may often be a series of rapid movements designed to further self-preservation, especially when the 'other vehicle' is sufficiently dangerous and can't stop (cf. Galileo, whose 'other vehicle' was the Catholic Church.)
In a closely related sense, this can mean simply collapsing - in this case the 'other vehicle' is usually the laws of physics (or logic, psychology or, in some cases, mere rhetorical force.)
The question of who should give way, and when, has occupied many, but so far nothing much more useful than the highway code has come of it.