:Stress shift:

The tendency in some languages, including English, to avoid stress on adjacent syllables (called a stress clash) by moving one stress (usually the first) to another syllable. A simple example is the phrase thirteen men which is usually pronounced ˈθɜːtiːn ˈmen rather than θɜːˈtiːn ˈmen, where the primary lexical stresses of the two words fall on adjacent syllables.

Also called iambic reversal.