Meaning and name origin
Rainer \ra(i)-ner\ as a boy's name is pronounced RAY-ner. It is of Old German origin, and the meaning of Rainer is "deciding warrior". Variant of Raynor. Related surnames are occasionally used as given names. Mount Rainier is an important landmark named for a British naval officer, but the Indian name was Tacoma or Tahoma, meaning "snowy peak". Modern use of Rainier (ray-NEER) may be influenced by Prince Rainier of Monaco. Poet Rainer Maria Rilke.
Rainer is not a popular first name for males but a very popular surname or last name for all people (#8620 out of 88799, Top 10%) (2000 U.S. Census).
Displayed below is a comparison of the popularity of the boy name Rainer and its variant forms. The only popular variation form ranked in the Top 1000/100 is Raymond (#264). (2014 statistics).