[From Manx Soc vol 2, Kelly's Manx Grammar]
The substantive and adjective agree generally in gender, and sometimes too in number; but an adjective singular is most frequently joined to a substantive plural: as deiney berchagh, rich men.
The place of the adjective in construction is after its substantive: as dooinney mie, a good man; ben aalin, a fair woman; mac ammyssagh, a dutiful son; inneen ghraihagh, a lovely nymph. Except drogh and shenn. Giare and lhag are also sometimes placed before their substantives: yn ghiare-veinn, yn lhag-ghooinney.
When an adjective comes after a substantive singular of the masculine gender, it retains its radical initial: as goo mie, a good report; thie mooar, a large house; tarroo puttagh, a pushing bull; dooinney builtagh, a quarrelsome man.
The adjective, after a substantive singular of the feminine gender, changeth its radical initial into its soft: ben vie, a good woman; inneen waagh, a pretty girl; cooish chluicagh, a crafty cause; eddin ghennal, a merry countenance.
When an adjective is placed before its substantive, the mutable initial of the substantive is changed into its soft, and the adjective must be of the masculine gender: as drogh-ghooinney, a bad man; drogh-yannoo, a bad action; shenn ven, an old woman.
All substantives plural, of what gender soever they be, will have adjectives after them beginning with their radical initials, and most frequently of the singular number: as deiney mie, good men; inneenyn mie, good women; eddinyn gennal, merry faces; skeeallyn snie, good news; deiney berchagh, rich men, not deiney berchee. Except in the vocative case plural, which always aspirates the initial of the following adjective: as chaarjyn ghraiagh.
Adjectives of the superlative (or English comparative) degree are always set after their substantives when comparison is signified, and make no change of the initial of the substantive whether it be masculine or feminine: as yn eddin s'gilley, the fairest face; yn laue s'lajer, the strongest hand; ta'n ven ny s'thollee na e sheshey, the woman is stronger than her husband. But when the superlative is used to express admiration, it is usually placed before its substantive without making any change in the initials: as s'gial yn eddin! how clean is the face! s'lajer e laue! strong is his hand! s'thollee ta'n ven! stout is the woman!
Rouyr, too much, is ever placed before its substantive, and makes no change of the initial: t'ou goaill rouyr bea, rouyr jannoo ort, you take too much trouble or plague upon yourself. And so is dy chooilley, every, ever placed before its substantive, and always makes the radical initial of its substantive change into its soft or secondary mute: as dy chooilley ghooinney, every man; dy chooilley ven, every woman.
Numerals are placed before their substantives, and make no change in their initials: as un dooinney, one man, three deiney, kiare, queig, &c.
Except daa, two, which makes the substantive following change its radical initial into its soft or secondary mute: as daa ghooinney, two men; daa ven, two women; daa phaitchey, two children. So un, one, before a feminine substantive: as un ven, one woman; un vooa, one cow; un ghoodee, a girl, or wench.
Ordinals are placed before their substantives, and change their initials into their soft: as yn chied ven, the first woman; yn nah ghooinney, the second man; yn bass ghooinney, the third man, yn chiarroo, yn wheiggoo, &c. Except words beginning with d, j, t, which suffer no change when joined to chied: as yn chied dooinney, the first man; yn chied towse, the first measure; yn chied jough, the first drink.