beneficial
The definition for beneficial is "Helpful." Used in a sentence: there is no doubt that eating vegetables is beneficial to one's health.
diffident
The definition for diffident is "Lacking self–confidence." Used in a sentence: The diffident student never raised her hand in class, even when she knew the answer.
lurid
The definition for lurid is "Causing horror, shocking." Used in a sentence: The lurid photos of the crime scene upset the jury.
periodic
The definition for periodic is "Occurring at regular intervals." Used in a sentence: The periodic innterruptions of the cuckoo clock prevented Li from concentrating.
scapegoat
The definition for scapegoat is "Someone who bears the blame for others." Used in a sentence: Audrey used her innocent baby brother as a scapegoat for the missing cookies.