the GNU version of the Collaborative International Dictionary of English
n. Any species of turbellarian worms belonging to Planaria, and many allied genera. The body is usually flat, thin, and smooth. Some species, in warm countries, are terrestrial.
The Century Dictionary and Cyclopedia
n. The typical genus of Planariidæ. P. torva is an example.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. free-swimming mostly freshwater flatworms; popular in laboratory studies for the ability to regenerate lost parts
Word Usage
"This experiment involved one of the most primitive forms of life, a type of worm called planaria."