[f. TWIN a. or sb. + -SHIP.] The condition of being twin, or a twin; the relation of a twin or twins. lit. and fig.
1674. N. Fairfax, Bulk & Selv., 107. It [an atome or leasting] has neither East Side nor West side; top nor bottom, nor any thing that speaks twinship to any thing else.
1796. Burney, Mem. Metastasio, I. 378. With all the tenderness of twinship.
1899. Griffith Jones, Ascent through Christ, II. ii. 28. The two streams of mental and organic life coalesce and begin that marvellous twinship which ends only at death.