amorous glance; making eyes at; covert flirtation
A yojijukugo describing a romantic or flirtatious look, often exchanged secretly. The second gloss extends the meaning to behind-the-scenes maneuvering or currying favor, but the core image is a sidelong amorous glance.
She cast an amorous glance at him.
During the meeting, the two were exchanging flirtatious looks.
秋波 alone means 'amorous glance' or 'bewitching look', often used in the phrase 秋波を送る. 暗送秋波 is the four-character compound that emphasizes the secretive or behind-the-scenes aspect.
A yojijukugo of Chinese origin, literally 'secretly send autumn ripples', where autumn ripples (秋波) metaphorically refer to a woman's alluring eyes. The phrase is used to describe covert flirtation or behind-the-scenes maneuvering.