The English word "foot" is a translation of the Latin term pes, plural pedes, which in turn is a translation of the Ancient Greek ποῦς, pl. πόδες. The Ancient Greek prosodists, who invented this terminology, specified that a foot must have both an arsis and a thesis, that is, a place where the foot was raised ("arsis") and where it was put down ("thesis") in beating time or in marching or dancing. The Greeks recognised three basic types of feet, the iambic (where the ratio of arsis to thesis was 1:2), the dactylic (where it was 2:2) and the paeonic (where it was 3:2).
In some kinds of metre, such as the Greek iambic trimeter, two feet are combined into a larger unit called a metron (pl. metra) or dipody.
Below are listed the names given to the poetic feet by classical metrics. The feet are classified first by the number of syllables in the foot (disyllables have two, trisyllables three, and tetrasyllables four) and secondarily by the pattern of vowel lengths (in classical languages) or syllable stresses (in English poetry) which they comprise.