the GNU version of the Collaborative International Dictionary of English
adj. Shaped like the Greek letter lambda (Λ).
The Century Dictionary and Cyclopedia
Having the shape of the Greek capital lambda (Λ): specifically applied in anatomy to the suture between the supraoccipital and the two parietal bones of the skull, which has this form in man. See cut under cranium.
Word Usage
"In one section, Ms. Falk declares: "Dart had mistakenly identified the lambdoid suture of the skull that had been imprinted on Taung's endocast as the lunate sulcus!""