Entry 1 sense Webster, 1913 Overtax /ōv'-ẽrt-ăksˌ/ · O·ver·tax · IPA /ˌəʊvə(ɹ)ˈtæks/ 01 v. t. To tax or to task too heavily; as, a job that overtaxed his physical energies. 1. To tax or to task too heavily; as, a job that overtaxed his physical energies.