Entry 1 sense Webster, 1913 Bacteriological /(băk*tē`rĭ*ō̇*lŏj"ĭ*kal)/ · Bac·te·ri·o·log·ic·al · IPA 01 a. Of or pertaining to bacteriology; as, bacteriological studies. 1. Of or pertaining to bacteriology; as, bacteriological studies.