source (n): the place something comes from or starts at, or the cause of something Use “source” in a sentence We are trying to trace the source of infection. I heard it from a reliable source. What is your main source of income? I can’t identify the source of the problem. The source of the infection has not yet been traced.

Examples of Source in a sentence Although the source of the infection could not be found, it was eventually cured with antibiotics. The source of her strength is the Lord, He being the foundation for everything good in the woman’s life. Each source for the plaintiff’s claim was proved faulty and the case was eventually dropped.