Subterestrial or Subterrestrial: How To spell?
The word Subterestrial is misspelled against Subterrestrial, an adjective meaning "Subterranean."
Subterrestrial has double "rr" is mispronounced as "r"Remember double 'RR' in between the strings subte & estrial which should not be misspelled with single 'R'
Wrong Spelling:  subte-r-estrial  Correct Spelling:  subte-rr-estrial 
Check more misspelled words of Subterrestrial to spell it correct.