spondee
noun
spon·dee ˈspän-ˌdē 
: a metrical foot consisting of two long or stressed syllables
spondaic
spän-ˈdā-ik
adjective or noun 
Word History
Etymology
Middle English sponde, from Middle French or Latin; Middle French spondee, from Latin spondeum, from Greek spondeios, from spondeios of a libation, from spondē libation, from spendein to make a libation; from its use in music accompanying libations — more at spouse
First Known Use
14th century, in the meaning defined above