Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
hui, interj., an exclamation of astonishment or admiration, hah! ho! oh! hui, homunculi quanti estis, Plaut. Rud. 1, 2, 65: hui, dixti pulchre! Ter. Phorm. 2, 1, 72: triginta? hui, percara est! id. ib. 3, 3, 25: hui, tam cito? ridiculum, id. And. 3, 1, 16: Ch. Prorsum nihil intelligo. Sy. Hui, tardus est! id. Heaut. 4, 5, 28: hui, quantam fenestram ad nequitiam patefeceris! id. ib. 3, 1, 71: videbam sermones: Hui! fratrem reliquit? Cic. Att. 6, 6, 3; 5, 11, 1: hui quam diu de nugis! id. ib. 13, 21, 5; Cael. ap. Cic. Fam. 8, 15, 2.