fifo fifish • fifteen · · · Info · Definitions · Synonyms · Characters · · fifo · · Text Latin · · Script 4 · · Length Definitions · · · (noun) inventory accounting in which the oldest items (those first acquired) are assumed to be the first sold. Synonyms: first in first out, FIFO. · · Noun Definition 1 Synonyms · · · first in first out · · Synonym 1 Characters · · f latin small letter f U+0066 i latin small letter i U+0069 o latin small letter o U+006F