s = seconds (mostly common)
m = minutes (eh)
h = hours (uh)
d = days (not been used yet)
w = weeks (also not been used yet)
f = fortnight (2 weeks, also not been used also)
mo = months (been used only 4 or 1 time(s))
y = year (also too)
d = decade (DUDE WHAT THE HE-)
mil = millennium (.)