a. [f. Gr. τρίχα triply + -τομ-ος cut + -OUS; cf. DICHOTOMOUS.]
1. Bot. Dividing into three branches; so branched that each successive axis divides into three.
1800. Misc. Tr., in Asiatic Ann. Reg., 273/2. Peduncles axillary,… trichotomous.
1806. J. Galpine, Brit. Bot., § 29. Aira…. Culm almost naked: pan[icle] spreading trichotomous.
1880. S. Yosino, in Sir E. J. Reed, Japan, II. 44, note. Its stem and branches are trichotomous.
2. Making three divisions, classes, or categories; involving or of the nature of trichotomy.
1855. N. Lindley, Introd. Jurisprudence, App. 85. The passages cited … are all against the trichotomous and in favour of the dichotomous division of culpa.
1899. Robertson, in Expositor, May, 351. A trichotomous psychology.
Hence Trichotomously adv.
1830. Lindley, Nat. Syst. Bot., 204. Flowers in regular cymes, branched bi- or trichotomously.
1853. Royle, Mat. Med. (ed. 2), 444. Panicles short, trichotomously divided.
