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.
incumbent
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.
punctual
The definition for punctual is "On time." Used in a sentence: Ron was worried when the usually punctual Amanda was late for the show.
ramble
The definition for ramble is "To wander, physically or in language." Used in a sentence: Professor Tan rambled during his lectures, frequently straying from the subject.
retroactive
The definition for retroactive is "effective as of a prior time or condition." Used in a sentence: The retroactive law made even past infractions punishable.