back·stab·bing 
/ˈbækˌstæbɪŋ/ noun
/ˈbækˌstæbɪŋ/ noun [noncount] US : harmful and unfair things that are said or done to hurt the reputation of someone
▪ She was hurt by her former friend's backstabbing.
▪ She was hurt by her former friend's backstabbing.
— back·stab·ber /ˈbækˌstæbɚ/ noun, plural back·stab·bers [count]
▪ She accused her former friend of being a backstabber.
/ˈbækˌstæbɚ/ noun, plural back·stab·bers [count] ▪ She accused her former friend of being a backstabber.
— backstabbing adjective always used before a noun
▪ a backstabbing liar
▪ a backstabbing liar
