What term is defined as a metrical foot that features the use of one stressed syllable and unstressed syllabe?

An iamb is a metrical foot consisting of an unstressed syllable followed by a stressed syllable.

Here are some examples of iambs:

* before

* above

* today

* repeat

* the wind

Many famous poems and plays use iambic pentameter, which is a line of poetry consisting of five iambs (ten syllables total).