1. Being or operating under the surface of the earth
   - subterranean 
2. Lying beyond what is openly revealed or avowed (especially being kept in the background or deliberately concealed)
   - subterranean, ulterior

See also: covert, subsurface

• proportional sampling
• proportional tax
• proportionality
• proportionally
• proportionate
• proportionately
• proportionateness
• proposal
• proposal of marriage
• propose
• proposer
• proposition
• propositional
• propositional calculus
• propositional logic
• propositus
• propound
• propoxyphene
• propoxyphene hydrochloride
• propping up
• propranolol
• proprietary
• proprietary colony
• proprietary drug
• proprietor