Side-line

Like most other fishes, the dragonet varies slightly in colour in different individuals, and at different seasons of the year. Mr. Pennant describes the pupils of the eyes to be of a rich sapphirine blue; the irides fine fiery carbuncle; the pectoral fins light brown; the side-line straight; the colours of the fish yellow, blue, and white, making a beautiful appearance when fresh taken.

Source: wiktionary

And whereas it also appears by the report aforesaid, that the western side-line of the said township of Cramahe, toward which the lots are numbered, has been correctly and truly surveyed: Be it therefore enacted [...]

Source: wiktionary

Along such a side-line one would progress until the desired objects were in sight.

Source: wiktionary

A younger man is more likely to resent being side-lined by a demanding infant and may fail to give a woman the support she needs.

Source: wiktionary