-logy

Words ending with -logy usually pertain to science or some theory.

logical

pathology

Science of diseases.

Sometimes people say pathological liar. This means the person lies so much that it has to be a disease.

cron

The software utility Cron is a time-based job scheduler in Unix-like computer operating systems.

chronological

Arranged in order by time.

-itis

A suffix used in pathological terms that denote inflammation of an organ ( bronchitis; gastritis; neuritis) and hence, in extended senses, nouns denoting abnormal states or conditions, excesses, tendencies, obsessions, etc. ( telephonitis; baseballitis).

sub

Below. Subway is the way below, in the ground.

infra

Below. Infrastrucutre and infrared comes to mind.