Short form of Russian adjectives
The majority of qualitative adjectives have short forms. Relational adjectives, and all adjectives that end in the suffixes -ск- and -ян- do not have short forms. Short form adjectives exist only in predicate nominative form. They have masculine, femine, neuter and plural forms and do not decline.
Short form adjectives are used after a linking verb, generally, after the verb быть to be which is omitted in the present tense.
Эта проблема была очень важна. - This problem was very important (the past tense).
Эта проблема очень важна. - This problem is very important (the present tense).
The short form of the adjective важный is used after the verb быть to be which is omitted in the present tense.
Short forms of adjectives are derived from long forms. The stem of the long form serves as the masculine short form and as the basis for feminine, neuter and plural forms that have endings -а, -о and -ы/-и, respectively. Plural forms will have the ending -и where the Spelling rule №1 will apply. Short-form adjectives do not decline.
The table below represents the short forms of adjectives готовый ready and хороший good:
If the stem of the adjective ends in a cluster of two or more consonants, the masculine short form has a vowel -о- or -е- inserted between the two final consonants:
The letter о is inserted if the stem of the adjective ends in -к. The letter о is also inserted in short forms of adjectives полный ful (short form: полон) and смешной funny (short form: смешон).
The letter е is inserted if the stem of the adjective ends in -н, except adjectives полный and смешной.
редкий- редок rare
важный - важен important
больной - болен sick, ill
The adjective маленький small has a special short form мал (other forms: мала, мало, малы).
For the adjective большой big, the word велик (other forms: велика, велико, велики) is used as the short form.
The adjective рад glad, happy (other forms: рада, рады) exists only in short form.