Which Word Should We Choose,
Formal or Informal?
We have already pointed out that formal style is restricted to formal situations. In general, formal words fall into two main groups: words associated with professional communication and a less exclusive group of so-called learned words.
These words are mainly associated with the printed page. It is in this vocabulary stratum that poetry and fiction find their main resources.
The term "learned" is not precise and does not adequately describe the exact characteristics of these words. A somewhat out-of-date term for the same category of words is "bookish", but, as E. Partridge notes, "'book-learned' and 'bookish' are now uncomplimentary. The corresponding complimentaries are 'erudite', 'learned', 'scholarly'. 'Book-learned' and 'bookish' connote 'ignorant of life', however much book-learning one may possess". 
The term "learned" includes several heterogeneous subdivisions of words. We find here numerous words that are used in scientific prose and can be identified by their dry, matter-of-fact flavour (e. g. comprise, compile, experimental, heterogeneous, homogeneous, conclusive, divergent, etc.).
To this group also belongs so-called "officialese" (cf. with the R. канцеляризмы). These are the words of the