pen·e·trom·e·ter 
(pĕn′ĭ-trŏmĭ-tər) also pen·e·tram·e·ter (-trămĭ-tər)
(pĕn′ĭ-trŏmĭ-tər) also pen·e·tram·e·ter (-trămĭ-tər)n.
1. A device for measuring the penetrating power of radiation, especially x-rays.
2. A device for measuring the penetrability of semisolids.