In musical terminology, divisi, or as typically printed “div.,” is an instruction to divide a single section of instruments into multiple subsections.
[1] This usually applies to the violins of the string section in an orchestra, although violas, cellos, and double basses can also be divided.
Other brass instruments can also be divided but it is not as frequent as with the Horn section.
After a divisi section, it may be cancelled by the instructions tutti, all'unisono.
For instance, Giuseppe Verdi's scores include directions for small sections of the chorus by metà ("half") or soli quattro soprani ("four sopranos alone").