heliotropyn.
Etymology: < helio- comb. form + Greek -τροπία turning. Compare French héliotropie.Previous versions of the OED give the stress as: heliˈotropy.
rare.
1883 XXIV. No. 6. 6 The author applies the name selenotropy to these motions, as contrasted with heliotropy produced by the sun.
This entry has not yet been fully updated (first published 1898; most recently modified version published online June 2019).