Thisetymology is missing or incomplete. Please add to it, or discuss it at theEtymology scriptorium. Particularly: “Perhaps related to the illiative case? See: "The origin of the Lithuanian illative" by Eugen Hill, Specht Litauische Mundarten Vol 2. p 256 footnote 3, and other sources.”
Adverbs formed from this suffix are often used with the verbeiti(“to go”), e.g.einablogyn,it is getting worse. Reduplication is also common for emphasis, e.g.didyn ir didyn,bigger and bigger.
Kalindra (2011) compares -yn to-ways,-ward, and-wise in English, although-yn is not restricted to directions. Alternatively, one may think of it as a comparative suffix like-er, which is usually how derived adverbs would be translated into English (as in the preceding examples), but this is distinct from the comparative degree of adverbs in Lithuanian.
Rimantas Kalindra (2011) “Some Lexical, Morphological and Syntactical Similarities and Differencies in Lithuanian, Italian and English Languages”, inStudies About Languages,→DOI, pages27–37
R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “-yn”, inGeiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies
