1) Greek boy name 
Latin, meaning: third. 
[law] Tertius is the Latin word for `third`, or `concerning the third`. The term is used in contract law to refer to an interested third party not privy to a contract. In the English Common Law system there is no recognition of the principle ius quaesitum tertio (a right in the third party to enforce performance) whereby a third party may e...
third.