An Etymological Dictionary of the German Language/heiser
heiser, adj., ‘hoarse,’ from MidHG. heiser, ‘rough, hoarse.’ with the variant MidHG. heis, heise, OHG. heisi, heis, ‘hoarse’; Goth. *haisa- is also indicated by AS. hâs; in MidE. besides hǫ̂se, an abnormal hǫ̂rse occurs, whence E. hoarse; so too MidDu. heersch, a variant of heesch (the latter also ModDu.); the r of the MidHG. and ModHG. derivative heiser is the widely diffused adj. suffix in bitter, lauter, hager, mager, &c. The Scand. háss, for the expected *heiss (Goth. *hais), also presents a difficulty. Some have attempted to connect the stem with that in hus-ten, which is impossible; hôs, hwôs, in husten, cannot, on account of the vowels, correspond to Goth. *haisa. Others, with greater reason, connect it with E. to whistle, AS. hwistlian, and with ModHG. wispeln, ‘to whisper’ (the Teut. root hais, hwī̆s, appears with a derivative k in AS. hwîskrian, OIc. hvískra, ‘to whisper,’ Du. heesch, ‘hoarse’).