final th (unvoiced)

math

bath
faith
fifth

myth

moth
month
mouth

south

sixth
seventh
eighth

ninth

tenth
both
booth

froth

teeth
tooth
north

birth

earth
mirth
dearth

hundredth

thousandth
millionth
billionth

final th + word endings (unvoiced)

months

booths
faiths
tenths

frothed

mouthed birthed unearthed