a prefix signifying alongside of, beside, beyond, against, amiss; as parable, literally, a placing beside; paradox, that which is contrary to opinion; parachronism.-a prefix denoting: (a) likeness, similarity, or connection, or that the substance resembles, but is distinct from, that to the name of which it is prefixed; as paraldehyde, paraconine, etc.; also, an isomeric modification. (b) specifically: (organ. chem.) that two groups or radicals substituted in the benzene nucleus are opposite, or in the respective positions 1 and 4; 2 and 5; or 3 and 6, as paraxylene; paroxybenzoic acid. cf. ortho-, and meta-. also used adjectively.