adjective
dimmer; dimmest
not bright or clear
not understood or remembered in a clear way
not likely to be good or successful
not good or favorable - used in the phrase dim view
informal :not intelligent :stupid or dim-witted
verb
dims; dimmed; dimming
to make (a light) less bright or to become less bright [+ obj]
to make (something) less strong or clear or to become less strong or clear [+ obj]