decimillimeter

(dmm)

   a metric unit of distance equal to 0.1 millimeter (10^-4 meter) or about 3.937 mils. The unit is used in civil engineering for stating the results of penetration tests of asphalt concrete, in which a needle is pushed into the concrete under specified conditions. Although this unit is allowed by some standards agencies, the use of compound prefixes such as decimilli- is not permitted in the SI.