The very poorly attested Slavic dialects of Rügen seemed to have had more in common with Polabian than with Pomeranian varieties.

Polabian is characterized by the preservation of a number of archaic features, such as the presence of nasal vowels, a lack of metathesis of Proto-Slavic *TorT; the presence of an aorist and imperfect verb tenses, traces of the dual number, and some prosodic features, as well as by some innovations, including diphthongization of closed vowels, a shift of the vowels o to ö, ü and a to o; a softening of the consonants g, k in some positions to d', t', an occasional reduction of final vowels, and the formation of complex tenses, many which are associated with the influence of the German language.

By the 18th century, Lechitic Polabian was in some respects markedly different from other Slavic languages, most notably in having a strong German influence.

It was close to Pomeranian and Kashubian, and is attested only in a handful of manuscripts, dictionaries and various writings from the 17th and 18th centuries.

[6][7] About 2800 Polabian words are known;[8] of prose writings, only a few prayers, one wedding song and a few folktales survive.

Immediately before the language became extinct, several people started to collect phrases and compile wordlists, and were engaged with folklore of the Polabian Slavs, but only one of them appears to have been a native speaker of Polabian (himself leaving only 13 pages of linguistically relevant material from a 310-page manuscript).

[citation needed] The most important monument of the language is the so-called Vocabularium Venedicum (1679–1719) by Christian Hennig von Jessen [de].

There are three theories:[28] Due to the poor attestation of Polabian, it is difficult to reconstruct a full morphology.

[29] As in all Slavic languages, Polabian has three grammatical genders: masculine, feminine and neuter.

The original term for thousand (Proto-Slavic *tysǫti) was replaced by the construction disąt pątstiďə.

[55] The negative pronouns are: nĕkătü (“nobody”), nic (“nothing”), nijadån (“not one, no”), niťidĕ (“nowhere”); all were formed using the prefix nĕ-/ni- , which phonetically cannot continue the Proto-Slavic *ni-, which would have developed as *nai-.

K. Polański believed that nai- was supplanted by ni- under the influence of the negative particle ni (“not”).

The future tense is formed by adding the auxiliary verb cą (“I want”) to the infinitive of the main verb of the present tense form: ci sneg ai̯t (“it will snow”), vån ci-să sḿot (“he will laugh”).

According to T. Lehr-Spławiński, A. E. Suprun and some other scholars, forms of the future tense could also be formed with the auxiliary verb met (“to have”): joz mom sijot (“I will sew”), K. Polyansky considered the verb met in these cases is a modal verb - “I must sew.” The use of the imperfect joz tех (“I wanted”), mes (“had”), ni-băs (“I wasn't”) and the aorist (sådĕ (“went”), våzą (“took”), påci (“fell”)) attested by a few examples.

The perfect II was probably formed under the influence of the perfect of the German language (formed using the verbs haben (“to have”) or sein (“to be”): ich habe geschrieben (“I wrote”)), as in Polabian it is also formed by the combination of the auxiliary verbs met (“to have”) and båi̯t (“to be”) and the passive participle: vån mo nodenă (“he found”), ją våpodenă (“fell”), ją ai̯ḿartĕ (“died”).