Entry 2 senses · 2 variants Webster, 1913 Nullifidian · Nul·li·fid·i·an · IPA /ˌnʌl.əˈfɪd.i.ən/ a. n. 01 a. Of no faith; also, not trusting to faith for salvation; -- opposed to solifidian. 1. Of no faith; also, not trusting to faith for salvation; -- opposed to solifidian. 02 n. An unbeliever. 1. An unbeliever.