1. (noun) a feeling caused by uneasiness or apprehension

• sinking feeling

1. (noun) a descent as through liquid (especially through water)

• descent

2. (noun) a slow fall or decline (as for lack of strength)

• decrease
• drop-off
• lessening

3. (noun) a feeling caused by uneasiness or apprehension

• anxiety

1. (noun) a descent as through liquid (especially through water)

• foundering
• going under
• immersion
• submergence
• submerging
• submersion
• settling
• subsidence
• subsiding

1. (noun) a descent as through liquid (especially through water)

• go down
• go under
• settle
• sink