riail1, f. (gs. -alach, pl. -alacha). Rule. 1. Regulation, principle. ~ a dhéanamh, a bhriseadh, to make, to break, a rule. Rialacha iompair, imeartha, bóthair, rules of conduct, of play, of the road. De réir na rialacha, in accordance with the rules. 2. Sway, authority; order. Bheith faoi ~ duine, to be ruled by s.o. Faoi ~ Shasana, under English rule. Níl ~ acu ar na páistí, they have no control over the children. Dream gan ~, unruly set. S.a. reacht 1. 3. Ecc: Code of discipline. ~ Cholm Cille, San Doiminic, the rule of St. Columcille, of St. Dominick. ~ chrábhaidh, rule of piety. 4. Jur: Order. ~ chúirte, rule of court. 5. Mth:~ na dtríonna, rule of three. 6. Graduated measure. An ~ a chur ar rud, to run the rule over sth. ~ ingir, plumb-rule. Surv:~ treorach, sighting rule. Mth:~ lúdraí, sector. ~ ochtréid, octet rule. Typ:~ (phráis, chruach), (brass, steel) rule. (Var:riaghail, gs. & npl. riaghla(cha))