Interline Definition

ĭntər-līn
interlined, interline, interlining
verb
To write or print between the lines of (a text, document, etc.)
Webster's New World
To insert between the lines.
To interline notes on pages.
Webster's New World
To fit (a garment) with an interlining.
American Heritage
To put an inner lining between the outer material and the ordinary lining of (a garment)
Webster's New World
Synonyms:
adjective
Of, relating to, or using more than one transportation line or system.
Webster's New World

Between lines.

Wiktionary

(transport) Between (with) two airlines.

Wiktionary