This book presents a 100% novel approach to A language-universal deductive calculus of all theoretically possible phraseological expressions (= phrasemes) is proposed, implemented in 51 rigorously defined notions. Nine major classes of phrasemes are established and lexemic idioms ( shoot the breeze ), lexemic collocations (pay a visit; helicopter parents ), lexemic nominemes ( the Northern Palmyra ) and lexemic clichés ( What’s your name?; to put it differently ); morphemic idioms ( forget ), morphemic collocations ( Londoner ~ Muscovite ), morphemic nominemes ( Greenland ) and morphemic clichés ( antidepressant ); and syntactic idioms ( Her be late?!?). An additional class of pragmatically constrained lexemic expressions is pragmatemes ( No parking; At attention!; Roger .). Each phraseme class is supplied with precise methodology for a lexicographic description; a number of lexical entries for representatives of all classes are given. The language data come from English and Russian. General Theory and Practice is meant as a contribution towards the elaboration of a unified notional system for linguistics.