(spatially) the back, the rear, behind / (temporally) later, afterwards, some time after the present / the rest

one's backside / the back, the rear (both spatially and temporally)

subsequently, afterwards

year

a grade, a school year / a year

years

nth-year student or pupil

twenty; 20

two days, a two-day period / the second day after some set point in time / the second day of the month

two