What does Rainer mean?
Rainer \ra(i)-ner\ as a boys' 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 an uncommonly occurring given name for men but a very prominent surname for both adults and children (#9598 out of 150436, Top 6%). (2000 U.S. Census)
Ray (#733 last year) and Raymond (#264) are the prominent alternative forms of Rainer (#unlisted). Adoption of these boy names reached its most widespread during 1930-1939 (usage of 0.9595%) and has become significantly less since (usage 0.5015%, down 47.7%), with the versions Ray and Raymond becoming less in vogue. Displayed below is an analysis of the usage of the boy name Rainer and affiliated names. (Top 1000 Baby Names Records, 2014)