surreptitious /sur-əp-tishˈəs/

1. Done by stealth or fraud
2. Stealthy

surreptiˈtiously adverb

• theoretics
• theoric
• theorics
• theories
• theorique
• theoriques
• theorisation
• theorise
• theorised
• theoriser
• theorisers
• theorises
• theorising
• theorist
• theorists
• theorization
• theorize
• theorized
• theorizer
• theorizers
• theorizes
• theorizing
• theory
• theory-laden
• theory of everything