The Collaborative International Dictionary of English v.0.48:
Encephalos \En*ceph"a*los\, n. [NL., fr. Gr. 'egke`falos; 'en in + kefalh` head.] (Anat.) The encephalon. [1913 Webster] In man the encephalos reaches its full size about seven years of age. --Sir W. Hamilton. [1913 Webster]