The words ending in "logy", a suffix inherited from Greek, can be divided into two categories: 
A. Words which have the sense of "saying or speaking".
ANALOGY, ANALOGIES = resemblance in some respects between things otherwise unlike
ANTILOGY, ANTILOGIES = a contradiction in terms of ideas  
APOLOGY, APOLOGIES = an explanation with expression of regret
CACOLOGY, CACOLOGIES = a bad choice of words 
DEKALOGY, DEKALOGIES = a group of ten novels 
DOXOLOGY, DOXOLOGIES = a hymn or verse of praise to God  
DYSLOGY, DYSLOGIES = dispraise  
ELOGY, ELOGIES = eloge (a funeral oration) 
EULOGY, EULOGIES = a speech or writing in praise
HOMOLOGY, HOMOLOGIES = similarity in structure and origin 
IDEALOGY, IDEALOGIES =  a systematic body of ideas 
MENOLOGY, MENOLOGIES = an ecclesiastical calendar
MISOLOGY, MISOLOGIES =  a hatred of debate or reasoning 
NEOLOGY, NEOLOGIES = a new word or phrase 
PARALOGY, PARALOGIES =  false reasoning 
TRILOGY, TRILOGIES = a group of three related literary works 
B. Names of sciences or departments of study.  
AEROLOGY, AEROLOGIES = science of the atmosphere  
AGROLOGY, AGROLOGIES = the science of soils in relation to crops  
ALGOLOGY, ALGOLOGIES = the study of algae   
APIOLOGY, APIOLOGIES = the study of bees  
S+ARCOLOGY, S+SARCOLOGIES = a system of architecture that integrates buildings with the environment  
AREOLOGY, AREOLOGIES = the study of the planet Mars  
ATMOLOGY, ATMOLOGIES = the science of water vapour   
T+AUTOLOGY = scientific study of oneself  
AXIOLOGY,AXIOLOGIES = the science of values   
BATOLOGY,BATOLOGIES = the study of brambles 
BIOLOGY, BIOLOGIES = the science of life 
BRYOLOGY, BRYOLOGIES = the study of mosses    
CETOLOGY,CETOLOGIES = the study of whales   
CHAOLOGY, CHAOLOGIES = the study of chaos   
CODOLOGY、CODOLOGIES =
CYTOLOGY, CYTOLOGIES = a study of cells    
DEMOLOGY, DEMOLOGIES = demography   
DOSOLOGY, DOSOLOGIES = the science of doses  
O+ECOLOGY, O+ECOLOGIES = an environmental science  
M,O,P,V+ENOLOGY, M,O,P,V+ENOLOGIES = the study of wines   
ETHOLOGY, ETHOLOGIES = the study of animal behaviour  
A+ETIOLOGY, A+ETIOLOGIES = the medical study of causes of disease  
FETOLOGY, FETOLOGIES = a branch of medicine dealing with fetus  
GEMOLOGY, GEMOLOGIES =  the science of gems 
GEOLOGY, GEOLOGIES = the science of the origin and structure of the earth 
C+HOROLOGY, C+HOROLOGIES = the science of measuring time    
IDEOLOGY, IDEOLOGIES =  the science of ideas  
KIDOLOGY, KIDOLOGIES = the art of kidding     
MIXOLOGY, MIXOLOGIES = the art of making mixed drinks   
MONOLOGY, MONOLOGIES = the act of uttering a monolog 
MYCOLOGY, MYCOLOGIES =  the branch of botany dealing with fungi
MYOLOGY, MYOLOGIES = the study of muscles   
NOMOLOGY, NOMOLOGIES =  the science of law 
NOOLOGY, NOOLOGIES = the science of the intellect  
NOSOLOGY, NOSOLOGIES =  a classification of diseases   
OECOLOGY, OECOLOGIES = ecology (an environmental science)   
P+OENOLOGY, P+OENOLOGIES = the study of wines 
OINOLOGY, OINOLOGIES = oenology (the study of wines) 
O+OLOGY, O+OLOGIES = a branch of knowledge 
ONCOLOGY, ONCOLOGIES = the science of tumors  
ONTOLOGY, ONTOLOGIES = the branch of philosophy the deals with being  
N,Z+OOLOGY, N,Z+OOLOGIES = the study of bird's eggs 
OPTOLOGY, OPTOLOGIES = the study of sight   
OREOLOGY, OREOLOGIES = orology (the scientific study of mountains) 
H+OROLOGY, H+OROLOGIES = the scientific study of mountains 
OTOLOGY, OTOLOGIES = the science of the ear  
OUROLOGY, OUROLOGIES = a branch of medicine dealing with the urinary tract
PEDOLOGY, PEDOLOGIEES = the scientific study of children
PELOLOGY, PELOLOGIES = study of mud and its curative effects   
PENOLOGY, PENOLOGIES = the science of the punishment of crime   
PODOLOGY, PODOLOGIES = the study of the feet   
POMOLOGY, POMOLOGIES = the study of fruits   
POSOLOGY, POSOLOGIES = a branch of medicine that deals with drug dosages  
PYROLOGY, PYROLOGIES = the scientific examination of materials by heat   
RHEOLOGY, RHEOLOGIES = the study of matter in the fluid state   
SEROLOGY, SEROLOGIES = the science of serums   
SEXOLOGY, SEXOLOGIES = the study of human sexual behaviour   
SINOLOGY, SINOLOGIES = the study of Chinese   
SITOLOGY, SITOLOGIES = the science of nutrition and diet  
A+THEOLOGY, A+THEOLOGIES = the study of religion  
TOCOLOGY, TOCOLOGIES = a branch of medicine dealing with childbirth   
TOKOLOGY, TOKOLOGIES = tocology (a branch of medicine dealing with childbirth 
TOPOLOGY, TOPOLOGIES = a branch of mathematics 
TYPOLOGY, TYPOLOGIES = the study of classification according to type 
UFOLOGY, UFOLOGIES = the study of unidentified flying objects   
O+UROLOGY, O+UROLOGIES = the branch of medicine dealing with the urinary tract
VENOLOGY, VENOLOGIES = the study of veins  
VINOLOGY, VINOLOGIES = the study of vines   
VIROLOGY, VIROLOGIES = the study of viruses  
XYLOLOGY, XYLOLOGIES = the study of the structure of wood 
ZOOLOGY, ZOOLOGIES = the science of animals 
ZYMOLOGY, ZYMOLOGIES = the science of fermentation