What is a lambda wing?
Indeed, it is due to resemblance with Greek letter 'lambda', though not the capital one ($ \Lambda $), but the small one: $ \lambda $.

I am attaching a pic of X-45 with me drawing a lambda over it. Typically, the wing has two taper ratios. The inboard wing tapers heavily, corresponding to legs of small lambda, and the outboard wing tapers slightly or do not taper at all.



Other examples include B-2 bomber: