Here is how L. Don and Florence Leet introduce this discontinuity in my favorite booklet on the early history and science of seismology :
When rocks that transmit earthquake waves at one speed lie on rocks that transmit them at a different speed, the boundary where the rocks meet at is called a “discontinuity.” The boundary discovered by Mohorovicic has been named after him, the “Mohorovicic discontinuity.” Since this is quite a mouthful, it is usually referred to simply as the “Moho.” The layer above the Moho is called the earth's “crust” and the layer below it the earth's “mantle.”
Indeed, Mohorovičić is difficult to say, spell and mark up. Moho is a much easier term. Moho also sounds somewhat Hawaiian, underlining its wave and quake association.
Keywords: earthquakes, seismology, boundaries within earth, Croatia
References and recommended reading
 Andrija Mohorovičić • Prominent Istrians [www.istrianet.org/istria/illustri/mohorovicic]
 L. Don and Florence Leet: Earthquake • Discoveries in Seismology. Dell Publishing Co., Inc, 750 Third Avenue, New York, N. Y. , 10017, USA, 1964; page 83.