orbiculate
adjective
or·bic·u·late ȯr-ˈbi-kyə-lət 
: circular or nearly circular in outline
an orbiculate leaf
see leaf illustration 
Word History
Etymology
borrowed from Latin orbiculātus, from orbiculus "circular figure, small disk" (from orbis "disk, circle" + -culus, diminutive suffix) + -ātus -ate entry 3 — more at orb entry 1
First Known Use
circa 1650, in the meaning defined above