"covering," Old English hod "a hood, soft covering for the head" (usually extending over the back of the neck and often attached to a garment worn about the body), from Proto-Germanic *hōd- (source also of Old Saxon, Old Frisian hod "hood," Middle Dutch hoet, Dutch hoed "hat," Old High German huot "helmet, hat," German Hut "hat," Old Frisian hode "guard, protection"), which is of uncertain etymology, perhaps from PIE *kadh- "to cover" (see hat).
Modern spelling is early 1400s to indicate a "long" vowel, which is no longer pronounced as such. Used for hood-like things or animal parts from 17c. Meaning "Foldable or removable cover for a carriage to protect the occupants" is from 1826; meaning "sunshade of a baby-carriage" is by 1866. Meaning "hinged cover for an automobile engine" attested by 1905 (in U.K. generally called a bonnet). Little Red Riding Hood (1729) translates Charles Perrault's Petit Chaperon Rouge ("Contes du Temps Passé" 1697).