A general term for columns having a small diameter. A capillary column may contain a packing or have the stationary phase supported on its inside wall. The former case corresponds to packed capillary column while the latter case corresponds to an open-tabular column. Due to the ambiguity of this term its use without an adjective is discouraged.
PAC, 1993, 65, 819. 'Nomenclature for chromatography (IUPAC Recommendations 1993)' on page 831 (https://doi.org/10.1351/pac199365040819)