Answer: Unrhymed iambic pentameter is called blank verse.
Explanation: Blank verse is a type of verse that consists in unrhymed iambic pentameter lines. In that way, as the foot of this type of verse is the "iamb", an unstressed syllable will always followed by a stressed syllable. Moreover, when using blank verse, every line will have ten syllables and five of them will be stressed syllables; however, as the blank verse is unrhymed, the stressed syllables will not rhyme.
