What does the last name Zehnder mean?

Answer 1

Variant of Zehner.

Zehner:

German (chiefly Bavaria, Austria, Switzerland, and Württemberg): occupational name for an official responsible for collecting, on behalf of the lord of the manor, tithes of agricultural produce owed as rent. The more prosperous tenants had to contribute wine and grain, those with smaller holdings fruit, vegetables, milk, cheese, beer, and poultry. The Middle High German term for this official was zehendære, a derivative of zehende'tenth part', 'tithe' (Old High German zehanto, from zehan 'ten').