As a noun, it is a formal agreement between two or more people that the law can enforce. As a verb, it means to make something smaller or tighter, or to catch a disease.
From Latin *contractus* 'a drawing together, an agreement', from *contrahere* 'to draw together, make a bargain'. The ideas of 'pulling together' and 'making an agreement' both come from this root.
The stress change (CON-tract vs con-TRACT) secretly signals whether it’s a noun or verb. Both meanings—legal contract and muscles contracting—come from the same idea of 'pulling things together.' Even 'contracting a disease' imagines the illness being drawn into you.
Complete word intelligence in one call. Free tier — 50 lookups/day.