subter-

(Latin: under, beneath, secretly, less than; formed from sub-)

subterannuating
subterannuation
subterfuge (s) (noun), subterfuges (pl)
subterraneal (adjective), more subterraneal, most subterraneal
Outdated, below the ground; subterranean: Under the shopping mall there is a large subterraneal parking lot for the customers to use.
subterranean (adjective) (not comparable)
1. Regarding something that is situated or operating beneath the surface of the Earth; underground: Some very religious people believe that there is a subterranean world where those who have committed crimes must live after death.
2. Hidden; secret: In the detective story, the culprit possessed a subterranean motives for committing the murder.
subterraneous (adjective) (not comparable)
1. Concerning something that exists under the surface of the Earth or is situated within the ground: Jack found out that there were subterraneous, or underground, springs and subterraneous passages leading down to the springs near his town!
2. Pertaining to something that is beyond what is openly revealed or avowed (especially being kept in the background or deliberately concealed): In the novel, Tom's subterraneous motive for murdering his grandfather was not disclosed until the end of the last chapter.
subterrestrial (adjective), more subterrestrial, most subterrestrial
Regarding something that lives or is situated nderground; subterranean: Many creatures are subterrestrial, for example earthworms, microscopic bacteria, fungi, and tiny insects.