From an earlier *silas, from Proto-Baltic *šil-, from Proto-Indo-European *sḱl̥-, the reduced grade of *skel-, *sḱel-, perhaps from *kel-, *ḱel- (“to dry up”) (whence also Latvian kalst “to dry up”) with an s-mobile, or perhaps by metathesis from *ks-el-, from *ḱes- (< *ḱs-eH-), *ḱsā- (“burned, dried up”) (whence Ancient Greek ξερός (xerós), ξηρός (xērós) “dry” and Sanskrit क्षायति (kṣā́yati) “to burn”). The meaning change was probably “dry, sandy place” > “forest on a dry, sandy place” > “pinewood, pine forest.” Cognates include Lithuanian šìlas, Ancient Greek σκέλλω (skéllō, “to dry up”).
sils m (1st declension)
- pine forest, pinewood (forest or grove composed of conifers growing in nutrient-poor sandy soil)
ķērpju sils ― lichen forest (i.e., where lichen grows)
piejūras sils ― coastal, seaside pine forest
paugurains sils ― hilly forest