the most gruff; having the roughest, most unfriendly manner or voice of all.
Superlative form of 'gruff' made by adding -est, the oldest and most basic way English shows the extreme degree of a quality.
English has two ways to make superlatives—adding -est for short words like 'gruff' versus 'most' for longer ones, and this exact system has lasted since Old English, making it one of language's most stable features.
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