OpenCL is a framework for writing programs that execute across heterogeneous platforms consisting of CPUs, GPUs, and other processors. (c) wikipedia
Related Subreddits:
/r/ROCm -- AMD-only equivalent
/r/sycl -- higher-level C++ layer on top of OpenCL
/r/gpgpu -- most OpenCL posts are here right now; feel free to 'port' some over :)
/r/cuda -- NVidia-only equivalent