1 GEISA
að, [Ulf. gaisjan or usgaisjan means to be alarmed, astonished; mid. Germ. gise and Swed. gäsa = to ferment; cp. Engl. yeast]:—to chafe, rage, of fire, Vsp. 57; láta gráðugan loga geisa, Mar. 530; hón (an excited lady) geisaði mjök, Nj. 57; látum Gamminn geisa, of a ship under sail, 135 (in a ditty); þeirra ofsi geisar hátt, their insolence runs high, Edda 146 (pref.); hversu sunnarlega geisar ríki föður þíns, Bær. 13; ofarr lét Grettir g. saxit í fyrra, Grett. 99 new Ed. Cod. Ups.
2 GEISA
II. to be panic-stricken, a notion which only appears in the word geiski: cp. geysask.