SUFFIXES- - other rules

When adding a suffix to a one-syllable word, if the root word ends in only one consonant and has only one vowel before it, and if the suffix begins with a vowel, then the consonant ending the root word will be doubled.

For example, when adding -ing to can, we double the n to end up with canning,  swimming,  running. Or begged, hottest, reddish, flatten, stopped, druggist, shipper, trekker, etc. 

This doubling of the consonant keeps the pronunciation from changing, as in:  hop + ing = hopping;  not  hope + ing = hoping (the o is long because of the i). 

Common endings beginning with vowels: -ing, -ice, -ous, -er, -ish, -ist, -ed, -age, -ible, -est, -ance, -ant, -able, -ably, -y, -al, -en, -ence, -ent, -ancy, -ency

The rule for multisyllable words is the same, but applies only when the last syllable of the root is accented, like in beginner and concurring, but not in begins or forgetful. 

Examples: 

For words ending in silent e, when the suffix begins with a vowel, that silent e is usually dropped before adding the suffix. For example, in take and -ing, we drop the silent e off of take, then add the suffix, and end up with taking.

Generally we do not let two vowels come too close together when we add a suffix beginning with a vowel,  so in many words wwe must drop the final “e”:   such as in mistake + able = mistakable, coming, famous, forgivable, desirable, moving, surer, smoking, bridal, gluable, nervous, behavior, believable… 

But we DO NOT DROP THE FINAL “e” IF THE MEANING of the word could change, or it could be misread:  singe +ing = singeing not singing.  Or ageing, blueing, lungeing, routeing, hoeing, twingeing, syringeing, forseeable, mileage, sizeable, etc.

Sometimes we DO NOT DROP THE FINAL “e” when it helps keep the “c” or “g” sounding soft:   knowledge + able = knowledgeable, courageous, peaceable, replaceable, traceable, noticeable…