logy

adj. lethargic, lacking enthusiasm, lacking vitality

The English suffix -ology or -logy denotes a field of study or academic discipline, and -ologist describes a person who studies that field. However not every field or study or discipline is an '-ology', for instance the study of childbirth is midwifery and a practitioner is a midwife.
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Adjective
1. stunned or confused and slow to react (as from blows or drunkenness or exhaustion)
(synonym) dazed, foggy, groggy, stuporous
(similar) lethargic, unergetic

(a.)
Heavy or dull in respect to motion or thought; as, a logy horse.
  

A combining form denoting a discourse, treatise, doctrine, theory, science; as, theology, geology, biology, mineralogy.
  

Synonyms and related words:
abeyant, apathetic, cataleptic, catatonic, dead, dopey, dormant, dull, flat, foul, groggy, heavy, in abeyance, in suspense, inactive, inert, languid, languorous, latent, leaden, lifeless, passive, phlegmatic, sedentary, slack, sleeping, sluggish, slumbering, smoldering, stagnant, standing, static, suspended, tame, torpid, unaroused