strain
A particular variety of a microbe, virus, or other organism, usually a taxonomically infraspecific one.
Example
“They say this year's flu virus is a particularly virulent strain.”
Other meanings
Hereditary character, quality, tendency or disposition.
“There is a strain of madness in her family.”
Any sustained note or movement; a song; a distinct portion of an ode or other poem; also, the pervading note, or burden, of a song, poem, etc.
Word history
From Old English "strēon".
Where this comes from
This definition is adapted from “strain” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.