colloq. Also thummy, -ie. [f. THUMB sb. + -Y, dim. suffix.] A little thumb; a kind of pet-name for the thumb.
1811. W. Tennant, Anster Concert, in Life (1861), 26. He never fashed his thummie.
1859. Lang, Wand. India, 265. The little finger replied: Who told you so, Thummy, Thummy?
1866. R. B. Paul, Lett., in Mem., xx. (1872), 353. Now thumby is beginning to make a grumble.