What is the X in X-mas?
1640s, from Latin analogus, from Greek analogos "proportionate, according to due proportion" (see analogy).
analogous a·nal·o·gous (ə-nāl'ə-gəs)adj. Similar in function but not in structure and evolutionary origin.
Similar in function but having different evolutionary origins, as the wings of a butterfly and the wings of a bird.
Similar in chemical properties and differing in chemical structure only with respect to one element or group.