epiboly
noun
epib·o·ly i-ˈpi-bə-lē 
plural epibolies
: the growing of one part about another
especially : such growth of the dorsal lip area during gastrulation
epibolic
ˌe-pə-ˈbä-lik
adjective 
Word History
Etymology
Greek epibolē addition, from epiballein to throw on, from epi- + ballein to throw — more at devil
First Known Use
1875, in the meaning defined above
Medical Definition
epiboly
noun
epib·o·ly
variants also epibole
i-ˈpib-ə-lē
plural epibolies also epiboles -lēz
: the growing of one part about another
especially : such growth of the dorsal lip area during gastrulation