Nick, Zess has no meaning that I am aware of in colloquial English. In one of the English phonetic alphabets "zess" is the name of the character used to replace "s" when it is pronounced like a z. For example: iz instead of is Denis

'zess' has no meaning in either US, UK, Austrailian, or any other English. Could the word be 'zest'? Zest = 1. enthusiasm and energy 2. the skin of a lemon, orange or lime when you use it for cooking Anna www.englishharvest.blogspot.com

It's not a word or even part of a word in American English (AE); Was the English teacher British? If so, then it probably means something in British English (BE). Even though they are more or less the same language, there are also many differences in usage between AE & BE; sayings/expressions, terminology, slang, pronunciation, etc.