Conjugation is the modification ("Beugung") of a verb, depending on person (I,you,he/she), number (singular/plural), tense (present,past) Declination is the modification of a noun depending on case ("Fall", in languages where cases exist) and number (singular/plural). Declination may also affect pronouns and adjectives (adj. are declined in German, but not in English) Flexion is a cover term ("Oberbegriff") for both conjugation and declination