The suffix "est" is used in English to form the superlative degree of adjectives. It indicates that something has the highest degree of a quality compared to others. For example, in the phrase "the tallest building," the word "tall" becomes "tallest" to show that this building is taller than all others. When using "est," it typically applies to one-syllable adjectives, such as fast becoming fastest or small becoming smallest. For adjectives with two or more syllables, the word "most" is often used instead, as in "most beautiful." This helps to clearly express comparisons among three or more items.