The process that gives rise to the rhombomere. This process pertains to the initial formation of a structure from unspecified parts. Rhombomeres are transverse segments of the developing rhombencephalon. Rhombomeres are lineage restricted, express different genes from one another, and adopt different developmental fates. [ https://www.worldcat.org/search?q=bn%3A0838580343 GOC:dgh GOC:dph GOC:cls GOC:jid http://purl.obolibrary.org/obo/go/references/0000021 ]