觀無量壽佛經義疏 3.194

3.194

「『得須陀洹，經半劫已成阿羅漢。』」須陀洹，此翻逆流，謂逆生死流，即初果也。三、結。

"‘They attain [the fruit of] the srotāpanna, and after half a kalpa become an arhat.’" Srotāpanna is translated here as "stream-enterer" [or "counter-stream"], meaning countering the stream of birth and death; it is the first fruit. Third, the conclusion.