[sup.pos.i.ti.tious] adj [L suppositicius, fr. suppositus, pp. of supponere to substitute] (1611) 1 a: fraudulently substituted: spurious b of a child (1): falsely presented as a genuine heir (2): illegitimate
2. [influenced in meaning by supposition] a: imaginary b: of the nature of or based on a supposition: hypothetical -- sup.pos.i.ti.tious.ly adv