The definition for colossal is "Immense, enormous." Used in a sentence: After pushing with all his might, Frank realized he could never move the colossal boulder.

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.

The definition for incumbent is "Necessary as a duty or responsibility." Used in a sentence: It was incumbent on Jack to attend his father's retirement party.

The definition for manifest is "Obvious." Used in a sentence: James finally made his affection manifest when he handed Jessica a red rose.

The definition for ploy is "A contrived plan." Used in a sentence: Sarah thought George's ploy of borrowing her notes was a cowardly way to ask her out.