| acicular | Apparently "needle-shaped" or "cigar-shaped" galaxy (Jacobi ellipsoid). Cf. Ogorodnikov (1965, 1967). |
| compact | Notation adopted from CGCG, where galaxies are listed as "compact" ("very compact", "extremely compact"), if they "might be easily mistaken for stars" (Zwicky), or from the Catalogue of Selected Compact Galaxies and of Post-Eruptive Galaxies (Zwicky 1971). |
| companion | Object in the neighbourhood of a galaxy listed in the present Catalogue; the object may be either a physical or an optical companion. |
| disrupted | Strong tidal disturbances. |
| distorted | Clear evidence of tidal effects; the structure is, however, not completely dissolved or disrupted. |
| disturbed | Weak tidal effects or suspicion that interaction with a nearby galaxy is taking place. |
| dwarf | Very low surface brightness; little or no central concentration of light on the red Sky Survey prints. |
| eruptive | Peculiar object with evidence of violent outflow of matter. Note that Zwicky (1971, p. XXX) defines "eruptive" in a different way; galaxies listed as "eruptive" in the present Catalogue would presumably be classified as "post-eruptive" by Zwicky. |
| integral | Flattened object with tips bent in opposite directions. |
| interaction | Synonym of "disturbed", used collectively for pairs or systems of higher order. |
| jet | Short, thin beam of outflowing matter. |
| peculiar | Greatly deviating from normal types in the common classification systems; classification is in general not possible. |
| plume | Extensive, diffuse, sometimes irregular formation of outflowing matter. |
| singular | Less prominent peculiarity than in objects denoted as "peculiar"; classification is often possible. |
| streamer | Long, broad beam of outflowing matter. |
| symbiotic | Double (triple, multiple) system with main bodies intermingled. |
| tail | Long, thin formation of outflowing matter; long jet. |
| unilateral | One-armed spiral galaxy. |
This work was in part financially supported by grants from the Swedish Natural Science Research Council and the Uppsala University Astronomical Observatory. The printing was made possible through the courtesy of the Royal Society of Science at Uppsala