n. The movement of a plant in response to gravity (either downwards or upwards)
the GNU version of the Collaborative International Dictionary of English
n. A disposition to turn or incline towards the earth; the influence of gravity in determining the direction of growth of an organ.
The Century Dictionary and Cyclopedia
n. In botany, growth downward, as shown in the roots of plants and sometimes in stems and rootstocks; the power or tendency to grow toward the earth.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. an orienting response to gravity
Word Usage
"Once plant life invaded the land it was subject to the action of gravity, and geotropism ( "earth-turning" G), involving an automatic and adaptive response to gravity, was developed."