Certain

ある

aru

(not specifically named, indeterminate, indefinite)

一定

ittei

(sure, positive, not doubting)

定か

sadaka

(sure, positive, not doubting)

某

bō-

(in reference to a specific person or thing that the speaker does not want to name directly)

特定の

tokutei no

(sure, positive, not doubting)

確か

tashika

(sure, positive, not doubting)

ある

aru

(having been determined but not specified)

とある

toaru

(having been determined but not specified)