dubious
The definition for dubious is "Questionable." Used in a sentence: Karl found Kevin's claim that he was sick dubious, as he had just seen him playing football.
gruff
The definition for gruff is "Rough or stern in manner or speech." Used in a sentence: Heidi's grandfather was gruff, barking stern orders and hardly smiling.
redouble
The definition for redouble is "To make twice as great." Used in a sentence: As the sun began to set, Brittany redoubled her effort to find the necklace she had dropped in the field.
regurgitate
The definition for regurgitate is "To pour out or throw back." Used in a sentence: The teacher wanted us to examine ideas rather than to regurgitate memorized facts.
stifle
The definition for stifle is "To repress or discourage." Used in a sentence: Amy tried ineffectively to stifle her giggles after she read Susan's note in class.