In 1934, Ole Kirk held a contest among his staff to name the company, offering a bottle of homemade wine as a prize.[1]:17 Christiansen was considering two names himself, "Legio" (with the implication of a "Legion of toys") and "Lego", a self-made contraction from the Danish phrase leg godt, meaning "play well." Later the Lego Group discovered that "Lego" can be loosely interpreted as "I put together" or "I assemble" in Latin.[3] Ole Kirk selected his own name, Lego, and the company began using it on their products.

Following World War II, plastics became available in Denmark, and Lego purchased a plastic injection moulding machine in 1947.[1]:25 One of the first modular toys to be produced was a truck that could be taken apart and re-assembled. In 1947, Ole Kirk and Godtfred obtained samples of interlocking plastic bricks produced by the company Kiddicraft. These "Kiddicraft Self-Locking Building Bricks"[4] were designed by Hilary Page.[5] In 1939, Page had applied for a patent on hollow plastic cubes with four studs on top (British Patent Nº.529,580) that allowed their positioning atop one another without lateral movement.[6][7] In 1944, Page applied an "Improvement to Toy Building Blocks" as an addition to the previous patent, in which he describes a building system based on rectangular hollow blocks with 2X4 studs on top enabling the construction of walls with staggered rows and window openings. The addition was granted in 1947 as British Patent Nº 587,206. In 1949, the Lego Group began producing similar bricks, calling them "Automatic Binding Bricks." Lego bricks, then manufactured from cellulose acetate, were developed in the spirit of traditional wooden blocks that could be stacked upon one another but could be "locked" together. They had several round "studs" on top, and a hollow rectangular bottom. They would stick together, but not so tightly that they could not be pulled apart. In 1953, the bricks were given a new name: Lego Mursten, or "Lego Bricks."