-th

1.
suffix (also -eth) forming ordinal and fractional numbers from four onwards (fourth; thirtieth).
Etymology: OE -tha, -the, -otha, -othe
2.
suffix forming nouns denoting an action or process:
1 from verbs (birth; growth).
2 from adjectives (breadth; filth; length).
Etymology: OE -thu, -tho, -th
3.
var. of -ETH(2).