二因 is read as にいん (niin) and means two causes.
にいん
niin
じゅうにいんねん
the twelve nidanas (continuum of twelve phases that lead to suffering)
はたち
20 years old
にりゅう
second-rate
にぶ
two parts
にじ
second
にじゅうよじかんせい
around-the-clock system
にき
two periods
にばん
にのつぎ
secondary
にごう
number two
によう
two flat things
ふたりづれ
party of two