cog / käg/ • n. a wheel or bar with a series of projections on its edge that transfers motion by engaging with projections on another wheel or bar: fig. she was only a very small cog in a big machine. ∎ each of such a series of projections.DERIVATIVES: cogged adj.
1. Projection or tenon at the end of a beam received into a corresponding notch or mortice in another beam. A cog-hold is therefore a connection using a cog.
2. Brick projecting and laid diagonally. See cogging