TEXT COMPLEXITY

words - number of words in text
sentences - number of sentences in text
word_len - mean word length in characters
sent_len - mean sentence length in words
LIX - LIX text complexity index
SMOG - SMOG text complexity index
FK - Flesch-Kincaid text complexity index (grade level)
syllables - number of syllables in text
polysyllabic_words - number of words that contain at least 3 syllables


LEXICAL COMPLEXITY

lemmas - number of lemmas, i.e., different words (e.g., 'go' represents 'going', 'goes' and 'went')
TTR - type-token ratio, i.e., ratio of different words to all words (lemmas to words)
RTTR - root type-token ratio
Uber - Uber lexical diversity index
Maas - Maas lexical diversity index
MTLD - MTLD index (Measure of Textual Lexical Diversity)
CVV - corrected verb variation

lexical_density - proportion of content words (words that convey meaning)
noun_abstractness - mean abstractness of nouns on the scale of 1-3
rare_5000 - proportion of words that are not among the most frequent 5000 Estonian words
rare_4000 - same with 4000 most frequent words
rare_3000 - same with 3000 most frequent words
rare_2000 - same with 2000 most frequent words
rare_1000 - same with 1000 most frequent words