phototonus

[foh-tot-n-uhs]

noun

Biology.

1. the normal condition of sensitiveness to light in organisms or their organs.

2. the irritability exhibited by cytoplasm when exposed to light of a certain intensity.

phototonus

/ ˌfəʊtəʊˈtɒnɪk, fəʊˈtɒtənəs /

noun

1. the condition of plants that enables them to respond to the stimulus of light

Other Word Forms

• phototonic adjective

Word History and Origins

Origin of phototonus¹

First recorded in 1870–75; photo- + tonus

Word History and Origins

Origin of phototonus¹

C19: from _photo- + Greek tonos _tone