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

Derived Forms

• phototonic, adjective

Other Words From

• pho·to·ton·ic [foh-t, uh, -, ton, -ik], 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