SUBTERRANEOUSLY
Scrabble letter values: S1U1B3T1E1R1R1A1N1E1O1U1S1L1Y4 = 20
Definition
SUBTERRANEOUSLY is the adverb form of SUBTERRANEOUS.
adjective SUBTERRANEOUS: being or operating under the surface of the earth.
Synonyms of SUBTERRANEOUS: subterranean