How to Form a Superlative Adjective

In general, superlative adjectives are formed by adding the suffix -est to an adjective. There are a few basic spelling rules to follow when forming a superlative adjective in this way:

    One-syllable words: Add -est to the word, as in strongest, tallest, and fastest. Sometimes this will require you to double the final letter of the original adjective, as in biggest and saddest.
    One- and two-syllable words ending in silent e: Add -st to the word, since the "e" is already in place. Note that doing this makes the "e" pronounced instead of silent. For example, rarest, finest and sanest.
    Two-syllable words ending in the letter y: Change the "y" to an "i" and add -est. For example, silliest, funniest, craziest.
    All other two-syllable words and words with additional syllables: Instead of adding a suffix, these words are made into a short adjective phrase by adding either most or least before the adjective. For example, most careful, most congenial, least restrictive, least invasive.