Put something out to tender
TENDER: (intransitive) followed by for: to make a formal offer or estimate for (a job or contract).
noun: the act or an instance of tendering; offer.
What does tender mean in put something out to tender ?
It means that in answer to a formal procedure making explicit that someone (company, business) is accepting propositions for doing a particular job for them, these propositions having to do with the means intended to accomplish this job and the price that is required (if that price has not been fixed), you make such a proposition.