chaetognathan vs. chaetognathous
cardiopulmonary vs. cardiorespiratory
cryptanalytic vs. cryptographic
cryptanalytic vs. cryptographical
cryptanalytic vs. cryptological
cataphoretic vs. electrophoretic
cytoarchitectonic vs. cytoarchitectural
colorimetric vs. colorimetrical
craniometric vs. craniometrical
counterterror vs. counterterrorist
carbonaceous vs. carboniferous
calligraphic vs. calligraphical
conspirative vs. conspiratorial
Congregational vs. Congregationalist
chromatographic vs. chromatographical
commemorating vs. commemorative
communicating vs. communication