Lamer means: A person lacking in maturity, social skills, technical competence or intelligence.. It is gaming vocabulary; common on Twitch streams, Discord servers, and in lobby chat across most modern multiplayer titles. It is generally derogatory or offensive; worth a quiet word about how it lands on the person being described. If your teen uses it, context will usually make the intent clear. A short, curious question about where they heard it is usually all that is needed to know whether to follow up.