Literally: tiger – look – watch intently – watch intently
Alternately: Vigilantly awaiting an opportunity. Watching intently for an opening. Like a tiger, lying still and staring down its intended prey as it waits for the chance to spring.
Notes: As always, the repeated character can be written with the doubling mark, as 眈々, without any change in meaning or pronunciation. Using the homophones 淡淡 or even the very similar-looking 耽耽 (note that the radical on the left in this case is “ear” rather than “eye”) is, however, an error.
This compound comes from a longer passage in the I Ching.