one's own pocket; personal profit
Used almost exclusively in the idiom 私腹を肥やす (to line one's own pockets). Refers to illicit personal gain, especially by someone in a position of trust.
See also: 私腹を肥やす
He lined his own pockets with public funds.
政治家が私腹を肥やすのは許されない。
It is unacceptable for politicians to enrich themselves.