rosh katan
n.— «As for the expressions (pronounced “rosh katan”—little head, vs. “rosh gadol”—big head). This expression comes from the IDF, and as most military language, doesn’t quite translate into normal language. A “rosh katan” (literally “little head,” and I actually think it is the original expression which derived most likely from “pinhead,” the contrast later came in as a complement) is someone that does exactly what he’s told. For instance, someone might be told to clean the barrel of their rifle. A “rosh katan” will strictly clean the barrel, perhaps leaving it useless because the trigger mechanism has sand in it, whereas a “rosh gadol” will clean the entire rifle and lubricate it so it’s ready for use and doesn’t rust.» —by Tamar Nitzan Joel on Software (New York City) Dec. , 2004. (source: Double-Tongued Dictionary)