apathetic
The definition for apathetic is "Showing little or no emotion." Used in a sentence: Carmine was concerned about his usually cheerful brother's apathetic attitude.
comprehensible
The definition for comprehensible is "Understandable." Used in a sentence: Shannon spoke slowly so her directions would be comprehensible to her foreign visitor.
heed
The definition for heed is "To pay attention to." Used in a sentence: "Heed my advice," the fortuneteller warned Sebastian when he tried to ignore her prophecy.
naive
The definition for naive is "Lacking worldy wisdom." Used in a sentence: The naive Simon assumed that everyone was as simple and kind as he was.
unscrupulous
The definition for unscrupulous is "Lacking principles." Used in a sentence: The unscrupulous salesman was fired for lying to his customers.