iambus
/aɪˈæmbəs; aɪ`æmbəs/ n
(pl ~es or -bi / -baɪ; -baɪ/) (also iamb / ˈaɪæm, ˈaɪæmb; `aɪˌæm, `aɪˌæmb/) metrical foot in poetry consisting of one short or unstressed syllable followed by one long or stressed syllable 抑扬格（诗的韵步, 每一短音节或非重读音节接以一长音节或重读音节组成一步）.