A drop.
"The medicine was administered as a single sie of liquid to treat his fever."
To sink; fall; drop.
"The heavy box will eventually sie down to the floor if you leave it on the edge of the table."
Gender-neutral subject pronoun, grammatically equivalent to the gendered pronouns he and she
"The teacher asked if Sie could help us understand the complex grammar rules of German."
The word "sie" comes from Old English sīgan, which originally meant to sink or descend. It traveled into modern usage through Middle English sien while retaining its core sense of going down or lowering.