"speak falsely, tell an untruth for the purpose of misleading," Middle English lien , from Old English legan , ligan , earlier leogan "deceive, belie, betray" (class II strong verb; past tense leag , past participle logen ), from Proto-Germanic *leuganan (source also of Old Norse ljuga , Danish lyve , Old Frisian liaga , Old Saxon and Old High German liogan , German lugen , Gothic liugan ), a word of uncertain etymology, with possible cognates in Old Church Slavonic lugati , Russian luigat? ; not found in Latin, Greek, or Sanskrit. Emphatic lie through (one's) teeth is from 1940s.

Old English treo , treow "tree" (also "timber, wood, beam, log, stake"), from Proto-Germanic *trewam (source also of Old Frisian tre , Old Saxon trio , Old Norse tre , Gothic triu "tree"), from PIE *drew-o- , suffixed variant form of root *deru- "be firm, solid, steadfast," with specialized senses "wood, tree" and derivatives referring to objects made of wood.

The line which divides trees from shrubs is largely arbitrary, and dependent upon habit rather than size, the tree having a single trunk usually unbranched for some distance above the ground, while a shrub has usually several stems from the same root and each without a proper trunk. [Century Dictionary]

In Old English and Middle English also "thing made of wood," especially the cross of the Crucifixion and a gallows (such as Tyburn tree , famous gallows outside London). Middle English also had plural treen , adjective treen (Old English treowen "of a tree, wooden"). For Dutch boom , German Baum , the usual words for "tree," see beam (n.).

The meaning "framework of a saddle" is from 1530s. The meaning "representation of familial relationships in the form of a tree" is from c. 1300. Tree-hugger , contemptuous for "environmentalist" is attested by 1989.

Minc'd Pyes do not grow upon every tree,

But search the Ovens for them, and there they be.

["Poor Robin," Almanack, 1669]