Free word groups and phraseological units

A word-group is the largest two-facet lexical unit comprising more than one word but expressing one global concept.
The lexical meaning of the word groups is the combined lexical meaning of the component words. The meaning of the word groups is motivated by the meanings of the component members and is supported by the structural pattern. But it’s not a mere sum total of all these meanings! Polysemantic words are used in word groups only in 1 of their meanings. These meanings of the component words in such word groups are mutually interdependent and inseparable (blind man – «a human being unable to see», blind type – «the copy isn’t readable).