Osilnica (, in older sources also Osivnica, Ossiunitz ) is a settlement in southern Slovenia. It is located on the left bank of the Kolpa River next to the border with Croatia. It is part of the traditional region of Lower Carniola and is now included in the Southeast Slovenia Statistical Region. It is the largest settlement and the centre of the Municipality of Osilnica.
Osilnica was attested in historical sources in 1365 as Ossiwniz (and as Ossawnitz in 1456–61 and Ossynnitz in 1498). The name may be derived from the adjective osiv 'grayish'. Derivation from *osьlьnica (< *osьlъ 'donkey' or *osьla 'whetstone') has also been proposed, but is less convincing for vocalic reasons.
