阿彌陀經疏 1.6

1.6

經者，法也、常也，法即舉直以措諸枉，繩墨以譬之；常即汲引而無竭，涌泉以況之，故言經也。《佛地論》云：能貫能攝故名為經，以佛聖教貫穿攝持所應說義，故言經也。

As for 'sūtra' (jing), it means standard (fa) and constant (chang). As standard, it is like lifting up the straight to set down the crooked, compared to a plumb line; as constant, it is like drawing water without exhaustion, compared to a bubbling spring; thus it is called a sūtra. The Buddhabhūmi-śāstra says: 'Because it can string together and hold together, it is called a sūtra; because the Buddha's holy teaching strings together and holds together the intended meanings to be spoken, it is called a sūtra.'