surreptitious /sur-əp-tishˈəs/

1. Done by stealth or fraud
2. Stealthy

surreptiˈtiously adverb

• pill bug
• pill bugs
• pilled
• pillhead
• pillheads
• pillicock
• pillicocks
• pilling
• pillings
• pillion
• pillioned
• pillioning
• pillionist
• pillionists
• pillion-rider
• pillions
• pillion-seat
• pillion-seats
• pilliwinks
• pillock
• pillocks
• pilloried
• pillories
• pillorise
• pillorised