Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
quindĕcim, num. adj. [quinque-decem], fifteen: QVINDECIM PONDO, Lex XII. Tab.: quindecim miles minas dederat, Plaut. Ps. 1, 1, 51; 1, 3, 112; Hor. C. S. 70: dies circiter quindecim, Caes. B. G. 1, 15; App. Mag. p. 304, 33.