From Longman Dictionary of Contemporary Englishvisorvi‧sor /ˈvaɪzə $ -ər/ noun [countable] 1 
DCCthe part of a helmet (=protective hard hat) that can be lowered to protect your face2 American English the curved part of a cap that sticks out in front above your eyes SYN peak British English3 TTCa flat object fixed above the front window inside a car that can be moved down to keep the sun out of your eyes4 DCCa curved piece of plastic that you wear on your head so that it sticks out above your eyes and protects them from the sun
DCCthe part of a helmet (=protective hard hat) that can be lowered to protect your face2 American English the curved part of a cap that sticks out in front above your eyes SYN peak British English3 TTCa flat object fixed above the front window inside a car that can be moved down to keep the sun out of your eyes4 DCCa curved piece of plastic that you wear on your head so that it sticks out above your eyes and protects them from the sunExamples from the Corpus
visor• The black visors of the hats the guards wore gleamed dully.• And the special pull-forward visor means you can increase the effectiveness of the hood over a greater area.• All he could see was tough grey jelly plastered across his visor.• Full transparent face shields or visors may be specified as an alternative and are sometimes an integral part of a safety helmet.• The prince was resplendent in his white naval uniform with braid on the visor of his cap.• She scanned the displays set round the visor on the inside of the helmet.Origin visor (1200-1300) Anglo-French viser, from Old French visiere, from vis; → VISAGE 