S / sub-tertĭus
adjective hapax

sub-tertĭus

fem. sub-tertia · neut. sub-tertium
of a number
less by a third of itself
less by a third of itself (i. e. that bears to another the ratio of 3 to 4), a transl. of the Gr. ὑπότριτος: numerus, Mart. Cap. 7, § 761.