1) Microbic 2) Microorganism 1) Microbic 
<biology, microbiology> Pertaining to microorganisms too small to be seen with the naked eye. ... (29 Oct 1998) ... 
Type: Term Pronunciation: mī-krō′bē-ăl Definitions: 1. Relating to a microbe or to microbes. Synonyms: microbic, microbiotic2
[adj] - of or involving or caused by or being microbes
microbial Caused by micro-organisms.
microbic adjective of or involving or caused by or being microbes; `microbial warfare`
A microscopic organism; a germ.