the.com/guide dog

means A specially trained dog that leads a blind or visually impaired person safely around obstacles, through traffic, and through daily life.

from A straightforward compound of 'guide' (from Old French 'guider,' to lead or direct, itself traced back to a Germanic root meaning 'to show the way') plus 'dog.' The practice is older than the phrase — dogs were depicted leading the blind in art centuries back — but formal guide dog training programs took shape in the 20th century, after wartime veterans blinded in combat spurred organized breeding and training schools in Europe and the US. The term itself simply names the job: a dog whose literal function is to guide.