Of a chemical compound having a ring with seven members(adjective)
WordNet. Princeton University. 2010.
Use "seven-membered" in a sentence
"Now that we have become more aware of the marvelous flexibility of carbon as a building block chemists may ultimately learn how to place five - and seven-membered rings precisely into a network of hexagonal rings so as to create nano structures of ordered three-dimensional complexity like the interconnecting girders in a steel-frame building."
"Buttmann has also shown that the elements of the ten-membered genealogy of Q (Genesis v.) and of the seven-membered of JE (Genesis iv.) are identical."