Two words
May be 2 words combined (fasta+culus) If not obvious, probably incorrect
cul.us N 2 1 NOM S M
culus, culi N (2nd) M [XBXCO]
buttocks; posterior; anus; (rude);
fast.a ADJ 1 1 NOM S F POS
fast.a ADJ 1 1 VOC S F POS
fast.a ADJ 1 1 ABL S F POS
fast.a ADJ 1 1 NOM P N POS
fast.a ADJ 1 1 VOC P N POS
fast.a ADJ 1 1 ACC P N POS
fastus, fasta, fastum ADJ [XXXDX] lesser
not forbidden; [~ dies => day on which praetor's court was open, judicial day];
*

Credits:
This, our local install of the popular standby Whitaker's Words, is possible thanks to the resurrection of the venerable project at William Whitaker's Words, where you will also find extensive documentation. The corresponding GitHub repository is where you can submit issues about missing forms and analyses.
This web interface by Walter M. Shandruk.