Merriam-Webster Collegiate Dictionary - est

 abbreviation eastern standard time EST  abbreviation  1. ~ablished  2. ~imate; ~imated EST  I. adjective suffix or adverb suffix  Etymology: Middle English, from Old English -st, ~, -ost; akin to Old High German -isto (adjective superlative suffix), Greek -istos — used to form the superlative degree of adjectives and adverbs of one syllable fattest latest, of some adjectives and adverbs of two syllables luckiest oftenest, and less often of longer ones beggarliest  II. verb suffix  or -st  Etymology: Middle English, from Old English ~, -ast, -st; akin to Old High German -ist, -ost, -est, 2d singular ending — used to form the archaic second person singular of English verbs (with thou) didst canst