An aqueous solution of an acid has a pH less than 7 and is colloquially also referred to as "acid" (as in "dissolved in acid"), while the strict definition refers only to the solute.
ɐn ˈeɪkwɪəs səlˈuːʃən əvən ˈæsɪd hɐz ɐ pˈiː ˈeɪtʃ lˈɛs ðɐn sˈɛvən ænd ɪz kəlˈoʊkwɪəli ˈɔːlsoʊ ɹᵻfˈɜːd tʊ æz "ˈæsɪd" æz ˈɪn "dɪsˈɑːlvd ɪn ˈæsɪd", wˌaɪl ðə stɹˈɪkt dˌɛfɪnˈɪʃən ɹᵻfˈɜːz ˈoʊnli tə ðə sˈɑːljuːt.