from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The growth of a living organism in response to gravity, as the downward growth of plant roots.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The movement of a plant in response to gravity (either downwards or upwards)
from 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.
from 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.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an orienting response to gravity
geo- + tropism (Wiktionary)