Members are collectively called lamprids (which is more properly used for the Lampridae) or lampriforms, and unite such open-ocean and partially deep-sea Teleostei as the crestfishes, oarfish, opahs, and ribbonfishes.

It ultimately derives from Ancient Greek lamprós (λαμπρός, "bright") + Latin forma ("external form"), the former in reference to brilliant coloration of opahs.

They vary greatly in size, too, ranging from less than 30 cm (12 in) in the sailfin moonfishes (Veliferidae) to Regalecus glesne, the longest of all living bony fishes, which may reach 17 m (56 ft) in length.

The upper jaw's protrusion is achieved in a unique way: the maxilla, instead of being ligamentously attached to the ethmoid and palatine, slides in and out with the highly protractile premaxilla.

Unlike their presumed relatives, they lack fin spines, however, and other authors have considered them to form a lineage just outside the Acanthomorpha, and the sister taxon of the Myctophiformes.

The order underwent its main radiation in the Paleocene period; the opah-like Turkmenidae were a family of lampriforms thriving at that time, but going extinct around the start of the Neogene, about 23 Mya.

Including fossil taxa, the classification of the Lampriformes in phylogenetic sequence, with the number of living genera and species, can thus be given as:[8] Basal and incertae sedis Suborder Taeniosomi