1. A fine or very thin thread or fiber: filaments of cloth; filaments of flax.
2. A slender or threadlike structure or part, especially:
a. A fine wire that is heated electrically to produce light in an incandescent lamp.
b. The stalk that bears the anther in the stamen of a flower.
c. A chainlike series of cells, as in many algae.
d. A long thin cellular structure characteristic of many fungi, usually having multiple nuclei and often divided by septa.
e. Any of various long thin celestial objects or phenomena, such as a solar filament.
[New Latin fīlāmentum, from Late Latin fīlāre, to spin, from Latin fīlum, thread; see gwhī- in the Appendix of Indo-European roots.]
fil′a·mentous (-mĕntəs), fil′a·menta·ry (-mĕntə-rē, -mĕntrē) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.