the.com/combination square

means A measuring tool with a ruled blade that slides through a head to mark 90° and 45° angles, check level, and gauge depth or height.

from Emerges from 19th-century machinist and carpentry workshops, where craftsmen wanted one tool to replace a try square, miter square, level, and rule. 'Combination' simply names the engineering trick — several single-purpose tools fused into one adjustable body via a sliding, lockable blade. Patents for combination-square designs cluster in the mid-to-late 1800s in the US, often credited loosely to toolmakers refining earlier try-square designs, though exact first-inventor claims are disputed and best held loosely rather than pinned to one name or date.