Definition of the word break in

The term "break in" refers to the process of making something new, especially clothing or shoes, more comfortable and functional by gradually wearing them in. The expression is believed to have originated during the mid-19th century when horse-drawn carriages were common in urban areas. The carriages required horses to pull them steadily and evenly, which meant that the harnesses, bridles, and other equipment needed to break in before they could deliver maximum performance. As equestrianism became more popular, the term "break in" entered the lexicon of popular usage to describe the process of training and conditioning horse gear and, by extension, any new item requiring a period of adjustment before it became fully functional. The use of "break in" in reference to clothing and shoes can be traced back to the early 20th century.