1.  arboreous(a = adj.all) arboreal, tree-living - inhabiting or frequenting trees; "arboreal apes"

2.  arboreous(s = adj.all) arboraceous, woodsy, woody - abounding in trees; "an arboreous landscape"; "violets in woodsy shady spots"; "a woody area near the highway"

3.  arboreous(s = adj.all) arboreal, arborescent, arboresque, arboriform, dendriform, dendroid, dendroidal, tree-shaped, treelike - resembling a tree in form and branching structure; "arborescent coral found off the coast of Bermuda"; "dendriform sponges"
Derived form noun arbor₁

1.  Having the form, constitution, or habits, of a proper tree, in distinction from a shrub. Loudon. [1913 Webster]

2.  Pertaining to, or growing on, trees; as, arboreous moss. Quincy. [1913 Webster]

arboreous, adj.
1 wooded.
2 arboreal.

N  vegetable, vegetable kingdom, flora, verdure, plant, tree, shrub, bush, creeper, herb, herbage, grass, annual, perennial, biennial, triennial, exotic, timber, forest, wood, woodlands, timberland, hurst, frith, holt, weald, park, chase, greenwood, brake, grove, copse, coppice, bocage, tope, clump of trees, thicket, spinet, spinney, underwood, brushwood, scrub, boscage, bosk, ceja, chaparal, motte, arboretum, bush, jungle, prairie, heath, heather, fern, bracken, furze, gorse, whin, grass, turf, pasture, pasturage, turbary, sedge, rush, weed, fungus, mushroom, toadstool, lichen, moss, conferva, mold, growth, alfalfa, alfilaria, banyan, blow, blowth, floret, petiole, pin grass, timothy, yam, yew, zinnia, foliage, branch, bough, ramage, stem, tigella, spray, leaf, flower, blossom, bine, flowering plant, timber tree, fruit tree, pulse, legume, vegetable, vegetal, vegetive, vegitous, herbaceous, herbal, botanic, sylvan, silvan, arborary, arboreous, arborescent, arborical, woody, grassy, verdant, verdurous, floral, mossy, lignous, ligneous, wooden, leguminous, vosky, cespitose, turf-like, turfy, endogenous, exogenous, green-robed senators of mighty woods, this is the forest primeval.