Definition of orthotropism in US English:

orthotropism

noun

Botany
  • The condition of being orthotropic; tendency to grow in a vertical direction, upwards or downwards.

Origin

Late 19th century; earliest use found in Sydney Vines (1849–1934), botanist. From ortho- + -tropism.

Pronunciation

orthotropism

/ˌɔːθə(ʊ)ˈtrəʊpɪz(ə)m/