- next after the sixty-ninth; being the ordinal number for 70.
- being one of 70 equal parts.
- a seventieth part, especially of one (1/70).
- the seventieth member of a series.
- (usually prenominal)
- being the ordinal number of seventy in numbering or counting order, position, time, etc: often written 70th
- (as noun)the seventieth in line
- one of 70 approximately equal parts of something
- (as modifier)a seventieth part
- the fraction equal to one divided by 70 (1/70)
adj.late 13c., from seventy + -th (1).