A compound may be labeled as dextrorotary by using the "(+)-" or "d-" prefix. Likewise, a laevorotary compound may be labeled using the "(−)-" or  "l-" prefix. The lowercase "d-" and "l-" prefixes are obsolete, and are distinct from the  "-" and "-" prefixes. The "-" and "-" prefixes are used to specify the enantiomer of chiral organic compounds in biochemistry and are based on the compound's absolute configuration relative to (+)-glyceraldehyde, which is the -form by definition. The prefix used to indicate absolute configuration is not directly related to the (+) or (−) prefix used to indicate optical rotation in the same molecule. For example, nine of the nineteen -amino acids naturally occurring in proteins are, despite the - prefix, actually dextrorotary (at a wavelength of 589 nm), and -fructose is sometimes called "laevulose" because it is laevorotary.
The - and - prefixes describe the molecule as a whole, as do the (+) and (−) prefixes for optical rotation. In contrast, the (R)- and (S)- prefixes from the Cahn–Ingold–Prelog priority rules characterize the absolute configuration of each specific chiral stereocenter with the molecule, rather than a property of the molecule as a whole. A molecule having exactly one chiral stereocenter (usually an asymmetric carbon atom) can be labeled (R) or (S), but a molecule having multiple stereocenters needs more than one label. For example, the essential amino acid -threonine contains two chiral stereocenters and is written (2S,3S)-threonine. There is no strict relationship between the R/S, the /, and (+)/(−) designations, although some correlations exist. For example, of the naturally occurring amino acids, all are , and most are (S). For some molecules the (R)-enantiomer is the dextrorotary (+) enantiomer, and in other cases it is the laevorotary (−) enantiomer. The relationship must be determined on a case-by-case basis with experimental measurements or detailed computer modeling.