simple past tense and past participle of drop by

plural of dropful

A single drop (of a liquid).

A brief visit, especially (politics) for the purpose of attracting voters or motivating one's staff.

plural of dropping in

Understanding is reached; one comprehends.

a saline liquid, used to administer medication to the eye

Third-person singular simple present indicative form of drop off

plural of air-drop

Third-person singular simple present indicative form of air-drop