The Collaborative International Dictionary of English v.0.48:
Retiring \Re*tir"ing\, a.
1. Reserved; shy; not forward or obtrusive; as, retiring
modesty; retiring manners.
2. Of or pertaining to retirement; causing retirement; suited
to, or belonging to, retirement.
Retiring board (Mil.), a board of officers who consider and
report upon the alleged incapacity of an officer for
Retiring pension, a pension granted to a public officer on
his retirement from office or service.