I. rein 1 /reɪn/ BrE AmE noun
[ Date: 1200-1300 ; Language: Old French ; Origin: rene , from Latin retinere ; ⇨ ↑ retain ]
1 . [countable usually plural] a long narrow band of leather that is fastened around a horse’s head in order to control it ⇨ bridle
2 . give (full/free) rein to something to allow an emotion or feeling to be expressed freely:
He gave free rein to his imagination.
3 . give somebody (a) free rein to give someone complete freedom to do a job in whatever way they choose
4 . keep a tight rein on somebody/something to control something strictly:
The finance director keeps a tight rein on spending.
5 . take/hand over the reins to take or give someone control over an organization or country:
Owens will officially take over the reins in a few weeks.
II. rein 2 BrE AmE verb
rein something ↔ in ( also rein something ↔ back British English ) phrasal verb
1 . to start to control a situation more strictly:
The government is reining in public expenditure.
2 . to make a horse go more slowly by pulling on the reins