An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) A large tract of land covered with trees and underbrush; woodland (Dictionary.com).
2) In → graph theory, a → graph which contains no → cycles. The connected components of a forest are → trees.

M.E., from O.Fr. forest, probably from L.L. forestis (silva) "the outside woods," from L. foris "outside."

Jangal "a wood, forest, a vast land with plenty of trees;" cf. Skt. jangala- "arid , sparingly grown with trees and plants."

The appearance of many differentially → redshifted→ Lyman alpha lines in → absorption in a → quasar's → spectrum, caused by intervening → hydrogen clouds along our → line of sight to the quasar.

→ Lyman; → forest.