surreptitious  – adjective obtained/done/made by stealth; secret or unauthorized; clandestine I surreptitiously stuck something in my pocket while my mom wasn’t looking.

tar·dy /ˈtärdē/Adjective: Delaying or delayed beyond the right or expected time; late. Slow in action or response; sluggish. I was tardy getting to my class. 

dec·adeNoun/ˈdekād/ A period of ten years. My older brother is a decade old.