Nounsource (of a river); fountainhead · source; origin; root

Nounsource (of a spring, etc.) · source (of payment, energy, knowledge, etc.); origin; wellspring

Nounsource (e.g. of a river); headwaters · origin of something continuous (language, culture, etc.)

Nounorigin of a word; derivation of a word; etymology

Nounroot; source; origin; cause