lambda baryon

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An electrically neutral baryon containing a strange quark and having a mass 2,183 times that of the electron and a mean lifetime of about 2.6 × 10⁻¹⁰ second.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun physics Any of three particles, having no electric charge and an isotopic spin of 1, composed of an up quark, down quark and either a strange quark, a charm quark or a bottom quark