Many native speakers use lame in everyday conversation. In reference to explanations or excuses, it means "weak and unconvincing." It also means "boring" in reference to things, and it can be used to refer to a person who is naive, socially awkward, or not cool.
You're not going to help me because you want to play video games all day? That's lame.
This party is lame. Let's go home.
I can't believe you're going out with him! He's so lame!
Words often used with lame
lame excuse: an excuse that isn't believable
lame joke: a joke that isn't funny
In less informal language, lame can also refer to an injured leg or foot, or to a person or animal that walks with difficulty as a result of that injury; this meaning is still used for animals, but today it is considered politically incorrect to use lame to describe an injured or disabled person. For example, someone might say "There are four lame sheep in that field," but it would be unusual and probably offensive to say something like "Mark has been lame since his car accident." It is also used as a verb and means "to injure somebody or something so they cannot walk normally."
lamely (adverb), lameness (noun)
The word lame dates from before 900 and comes from the Old English word "lama."