from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The turning or bending movement of an organism or a part toward or away from an external stimulus, such as light, heat, or gravity.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. the turning of an organism in response to a stimulus, either towards or away from the stimulus
- n. viral tropism, or which type of tissue supports a certain virus
from the GNU version of the Collaborative International Dictionary of English
- n. Modification of the direction of growth, caused by some external influence, such as light; -- sometimes used for motion of an organism toward or away from an external stimulus, more properly called
from The Century Dictionary and Cyclopedia
- n. In biology, growth, bending, orientation, or locomotion of organisms, or of parts of organisms, in relation to external agents.
- n. In a stricter use, the growing or bending of organisms, or of parts of organisms, in relation to external agents.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an involuntary orienting response; positive or negative reaction to a stimulus source
From -tropism.(American Heritage® Dictionary of the English Language, Fourth Edition)