Immersed

1. Deeply plunged into anything, especially a fluid.

2. Deeply occupied; engrossed; entangled.

3. (Bot.) Growing wholly under water. Gray.

Definition: deeply involved with
Antonyms: ignorant, neglectful, negligent

Tutor's tip: It would not be surprising to see a botanist "immersed" (engrossed, absorbed) for hours in the study of the "emersed" (standing out above the water) parts of lily pads.