As nouns the difference between fasti and fasts
is that fasti is the calendar in Ancient Rome, which gave the days for festivals, courts, etc., corresponding to a modern almanac while fasts is plural of lang=en.
As a verb fasts is
third-person singular of fast.
fasti
English
Noun
(
en-plural noun)
The calendar in Ancient Rome, which gave the days for festivals, courts, etc., corresponding to a modern almanac.
Records or registers of important events.
(
Webster 1913)
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fasts
English
Noun
(head)
Verb
(head)
(fast)