Is it ensure, insure, or assure?
a growing together; concrescence
Latin confluentia 'act of flowing together'
early 15c., from Late Latin confluentia, from Latin confluentem (nominative confluens), present participle of confluere "to flow together," from com- "together" (see com-) + fluere "to flow" (see fluent).
confluence con·flu·ence (kŏn'flōō-əns)n. A flowing or meeting together; a joining.
A flowing together of two or more streams or two or more glaciers.
The point of juncture of such streams or glaciers.
The combined stream or glacier formed by this juncture.