Property relativizing determiner / unary quantifier constructor. {kai'i} introduces a predicate whose first argument slot becomes filled by the property made by taking the bridi in which this {kai'i} appears and putting {ce'u} into the argument slot in which this {kai'i} argument was located. Put formally, "kai'i brodi cu brodu" = "lo ka ce'u brodu cu brodi". Additionally, a {kai'i} term has a rightward logical scope, like quantifiers and adverbials.
kai'i can be used to rephrase quantifiers as predicates, e.g. "ro da poi mlatu cu mabru" = "kai'i kampu be lo mlatu cu mabru"; "so'u remna cu kakne su'o simsa" = "kai'i zilrirci/so'umpu be lo remna cu kakne kai'i nartolkau/su'ompu be lo simsa". Other usage examples: "kai'i se snada be mi mo'u pagre lo rirxe" = "I succeeded to cross the river"; "falgau lo patxu fa kai'i snuti" = "making the pot fall was an accident, was unintentional"; "xunre je cukta fa kai'i se sisku be mi" = "A red book is what I'm searching for"; "kai'i dzaze'a cu pagzu'e" = "the number of participants is increasing". See also kau'u, soi'a.