STRATA is a playable word

stratum Scrabble® Dictionary

noun
pl. stratums or strata
a layer of material
31 Playable Words can be made from "STRATA"
   2-Letter Words (5 found)
   3-Letter Words (11 found)
   4-Letter Words (8 found)
   5-Letter Words (4 found)
   6-Letter Words (3 found)