Entries linking to tadpole
c. 1300 (late 12c. as a surname), polle, "hair of the head; piece of fur from the head of an animal," also (early 14c.) "head of a person or animal," from or related to Middle Low German or Middle Dutch pol "head, top." The sense was extended by mid-14c. to "person, individual" (by polls "one by one," of sheep, etc., is recorded from mid-14c.)
Meaning "collection or counting of votes" is recorded by 1620s, from the notion of "counting heads;" the sense of "the voting at an election" is by 1832. The meaning "survey of public opinion" is recorded by 1902. A poll tax, literally "head tax," is from 1690s. Literal use in English tends toward the part of the head where the hair grows.