This paper introduces a novel non-orthogonal multiple access (NOMA) concept named waveform-domain NOMA, which proposes the coexistence of different waveforms in the same resource element (RE). Regarding the demands of each user equipments (UEs), appropriate waveforms are assigned intelligently and decoded at the receiver side properly. Since the performance gain of power-domain NOMA compared to multi-user multiple-input-multiple-output (MU-MIMO) degrades in the case of successive interference cancellation (SIC) and channel estimation errors, NOMA is not considered as a work-item in 3GPP anymore. The novel waveform-domain NOMA concept provides a remedy for the problems of the power-domain NOMA scheme as well as flexibility in terms of reliability, latency, and energy efficiency. To mitigate SIC errors, low-density parity-check (LDPC) codes aided soft interference cancellation technique is used. As numerically evaluated, the proposed waveform-domain NOMA scheme outperforms the conventional power-domain NOMA in the power-balanced scenario.