The Proto-Indo-European word *hₐeĝros
Word *hₐeĝros
Meaning pasture, field
See also Linear B: a-ki-ti-ri-ja ‘wild’
Thracian: argilos ‘mouse’
Synonyms *hₐérh₃wr̥, *wélsu-

Comments
Skr. ajra, Gk. agros, Lat. ager, Umbrian ager, Goth. akrs, Eng. æcer/acre, Arm. art/ard, Gm. achar/Acker, ON akr

Other words that might be of interest
*ĝhðem-, ĝhðom- ‘earth’, *korpa ‘rock’, *dheu-1 ‘dust, smoke, vapor’, *dór-u- (nom-acc. dóru, gen. derw-ós) ‘tree’, *h₄ék̂mōn ‘stone’, *pérkʷus ‘oak’, *pē(n)s- ‘dust’, *samatha- ‘sand’, *der-, drew- ‘tree, wood’, *bherĝh- ‘mountain, hill’, *bʰerĝh- ‘high, hill’, *dóru ‘wood, tree’, *dhéĝhōm ‘earth’, *gʷorhₓ- ‘mountain, forest’, *h₁er- ‘earth’, *hₐeig- ‘oak’, *hₓihₓlu ‘mud, swamp’, *kerdhehₐ- ‘herd, series’, *wrētos ‘herd, flock’, *kʷrésnos ‘tree, brush(wood)’, *leh₁w- ‘stone’, *lep- ‘stone’, *mai- ‘soil, defile’, *penk- ‘mud, damp’, *pel(i)s- ‘stone, cliff, rock’, *peru- ‘rock’, *samh̥xdhos ‘sand’, *hₐeĝrehₐ- ‘hunt’, *kolh₁ōn ‘hill’, *pl̥th₂w-ihₐ- ‘country, land’, *poh₂imén- ‘herdsman’, *wéstor- ‘herdsman’, *widhu ‘tree, forest’