A Strain

1. (archaic) Race; lineage, pedigree.
2. (biology) A particular variety of a microbe, virus, or other organism, usually a taxonomically infraspecific one. Coordinate terms: cultivar, quasispecies, variety
3. (figurative) Hereditary character, quality, tendency or disposition. Synonyms: A Propensity, A Proneness
4. (music, poetry) 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. Synonyms: A Theme, A Motive, A Manner, A Style
5. Language that is eloquent, poetic, or otherwise heightened.(The addition of quotations indicative of this usage is being sought:)
6. (rare) A kind or sort (of person etc.).
7. (obsolete) Treasure.
8. (obsolete) The blood-vessel in the yolk of an egg.