It’s 1860 in a small county seat somewhere in the United States. A lawyer has been in his office all day, meeting a few clients and taking care of some paperwork. At some point during the day, his daughter while doing a few errands, stops in to see him. She has her six-month son with her.
Later that afternoon, the lawyer pens part of a legal document for an estate he’s helping settle. The document refers to the children of the deceased as “infant heirs.”
Before he leaves for the day he writes a letter to his sister. In that letter he tells his sister “my daughter brought the baby to see me this afternoon. The infant and mother are doing fine–we are thankful for God’s Blessings and hope you are hale and hearty as well.”
Twice he used the same word: infant.
When he wrote “infant” in the legal document it was used in the legal sense–typically referring to someone under the legal age of majority. That infant could have been as old as 17 or 20, depending upon the time period and the gender.
When he wrote “infant” in the letter to his sister, he used it the way a layman would: someone young enough to wear diapers.
Same word. Two different meanings depending on the context.
Words in legal documents are used in the legal sense. Make certain you know what that sense was.