Keren is a word whose multiple connotations have sometimes caused confusion. Its primary meaning is horn. Keren is sometimes used to refer to the shofar, the rams horn we blow on Rosh Hashanah, and also to the legal category of damage inflicted by an animals horn.
Secondarily, keren came to mean ray, or something projected from a point. The words for X-rays, cathode rays and light rays in modern Hebrew all come from keren.
An additional meaning of keren is fund or capital, as in Keren Kayemet LYisrael, the Jewish National Fund. The first mishnah in tractate Peah lists mitzvot whose reward we enjoy in this world like interest, while the capital (keren) is stored up for the world to come. This derives from the previous sense of keren as a source of power.
These diverse but related meanings of the word keren led to the Christian misconception, once widely held, that Jews have horns. After Moses collects the second version of the two tablets, the Torah describes how Moses was unaware that his face radiated light, karan or (Exodus 34:29).
Rashbam, Rashis grandson, cautions in his commentary that anyone who thinks, based on this verse, that Moses had horns, is simply a fool. However, the Vulgate mistranslated karan or as horns of light, leading to the widespread depiction of Moses with horns in Christian art, most famously in Michelangelos sculpture, Moses, at the church of San Pietro Invincula in Rome.