Wiktionary
straight chain
n. (context chemistry English) A structural element of a molecule consisting of an unbranched sequence of atoms or simple groups, especially such a sequence of methylene groups in a aliphatic compound
WordNet
straight chain
n. an open chain of atoms with no side chains
Usage examples of "straight chain".
Consisting of a straight chain of carbon atoms, with hydrogen atoms along its length, and a carboxyl growth at one end, Oleic acid is the most widely distributed example of which lipid component?
On awakening and recalling this dream fragment, Kekule realized instantly that the solution to the benzene problem was a hexagonal ring of carbon atoms rather than a straight chain.