subterreneanadj.

1653 J. Howell German Diet sig. Aa2^v Among other Rivers ther is Guadiana which playes bopiepe with passengers, for she suddenly steales away out of sight, and runs aboue 20. Miles in subterrenean Caverns under ground.

1670 J. Pettus Fodinæ Regales Introd. Many do write of Subterrenean Trees, Serpents, Fishes, &c.

1703 S. F. Egerton Poems Several Occasions 7 Pierc'd to the gloomy Ray, Where subterrenean Fires, in silence play, Like the faint Glimps of an imprison'd Day.

1816 T. L. Peacock Headlong Hall (ed. 2) x. 140-1 You all know the fable of the buried Pict, who..called out with a voice like subterrenean thunder: I perceive the degeneracy of your race by the smallness of your little finger!

1895 J. Mackie Sinners Twain vii. 67 That cold and crystal stream.., pierced its way between cyclopean blocks of sandstone, and through black subterrenean passages.

1919 Engin. & Contracting 21 May 529/1 Great subterrenean beds of coal.

1990 Behaviour 114 258 The middle ear of Spalax was characterized by some features which are convergent in many other specialized herbivore and insectivore subterrenean mammals.

2000 R. Sukenick Narralogues 33 Revolutions..turn into mirrors of regimes they've destroyed, while the subterrenean effects of a mutiny on the culture may be enduring.