biennium
n.
"space of two years," by 1851, from Latin biennium "two years, a period of two years," from bi- + annus "year" (see annual). For vowel change, see biennial.
〔李〕[bi-=two二；enni=year年；-um n.=thing物→“the time of two years两年的时间”→] n. period of two years两年