Abstract
<jats:p>The article systematises the information about word-forming pleonasm in the case of the suffix -ьнъ gained from a tergo indices (SJS and eight separate monuments from the early stage of Slavic literature) and analyses its compatibility as a secondary adjective suffix. The overview shows that adjectives without a typical adjectivising formant most often take on -ьнъ, which is probably due to the intralingual need to strengthen the faded indicators of belonging to the class of adjectives. Much less often, the suffix is added to stems with a word-forming element typical of adjectives, and most often this element is the possessive suffix -ов-/-ев-. Adjectives with the secondary suffix -ьнъ are not equally represented in the studied texts. If the percentage of their presence in the SJS corpus, which is 4.4%, is taken as an average value, then almost all the monuments examined deviate from it by up to 2 points in one direction or the other. Only the Didactic Gospel of Constantine of Preslav with its 9.7% pleonastic formations exceeds more than twice the average value. This affinity for secondary adjectives with the suffix -ьнъ deserves special attention in the future in studies of the language of the Preslav writer or of works attributed to him.</jats:p>