Gish
Gish is a /tg/ term relating to character classes, and specifically refers to a character who is capable of both melee combat and magic with relatively equal adeptness.
Gish originated from Dungeons & Dragons, where the githyanki had an elite caste known as the gish; githyanki using the multiclassing option to become fighter/wizards of considerable lethality. The archetype stuck fast in the D&D munchkin consciousness and it has remained a fixture of /tg/ ever since. The concept is referred to in homage to the githyanki, who started it all.
Traditionally, most gishes are the result of multiclassing, or dual-classing, or hybrid classing, depending on edition. However, certain classes have increasingly been designed to support this from the ground up, due to certain inefficiencies in the multiclassing approach - most notably, the XP Tax.
However, most "made" gish-classes have traditionally been "warriors, with a little magic"; examine the Paladin (fighter with some low-level Cleric spells and tricks) or the Ranger (a fighter/low-level druid blending). More melee capable mage types have been a rarity; the Swordmage of 4th edition D&D, or the Bladesinger Wizard and Stone Sorcerer of 5e, for example.