digraph < gh >

regex dictionary strings:

Cight$: fight, flight,  plight, blight, bright, sight, slight, tight, wright, night, might, right, light

Cigh$: sigh, nigh, high

Vigh$: weigh, neigh, inveigh, sleigh, 

aight$: /eɪ/: straight

eight$ /eɪ/: eight, weight, freight, 

eight$ /aɪ/: height, sleight (cf. heist, feisty)

ought$ /ɔ/  : ought, sought, thought, bought, brought, fought, wrought

ought$ /aʊ/: drought, plough, bough (Frazer's Golden Bough), Doughty, Dougherty (BrE forvo)

aught$ /ɔ/ :aught, caught, fraught, onslaught, distraught

augh /æ/: laugh(ter)

righteous:

ignite vs ignition

right vs righteous

CJB:

   "One cause can be illustrated with righteous.  If the reader considers ignite and ignition--with "sh" for //t//--and quest with question--with "ch" for //t//--, it will be evident that when  //t// is followed by a prevocalic light vowel that becomes /y/, the combination /ty/ becomes "sh" unless the //t// is immediately preceded by //s// (or more generally, any fricative sound allowed in this position--//f  s// and the sounds we spell "th" and "sh."  Notice that the //s/ in question is pronounced "sh."  What about righteous?  It has two anomalies:  the heavy "i" does not get lightened in righteous the way it does in ignition; and /ty/ becomes "ch" rather than "sh."  The reason for both irregularities is found in the silent "gh," which was a fricative before it fell out--which happened AFTER /ty/ had become "ch."  Further, this fricative made the vowel long (the old long vowels are the source of today's heavy vowels).  Righteous has to be marked in the lexion as simply irregular unless one wishes to posit the fricative in its underlying form and have a rule deleting it that is ordered to operate later than the other changes have taken place--a dubious analysis for a single exception.
    The way in which analogy can violate a system (as well as create system-conform phenomena) is seen in many stress phenomena.  Grimáce is losing the stress on its final syllable to resemble words having finale unstressed -ace like surface, solace, furnace, and terrace--even though these are not verb.  The verb frequent is losing its final stress to make it like the adjective spelled the same way--even though we do not see this occurring in the verbs absent and present.  Analogy makes some things fit the system better, but it often fails to do the job sufficiently thoroughly:  Forestressing the verb frequent causes it to violate the rule that  stresses the final syllable of verbs ending in -ent (including those in -vent like prevent, invent, etc.).  Where does this leave the adjective (and non) intent?"