When the termination begins with a vowel, the final e is omitted: e.g., sale, salable; bride, bridal; force, forcible. Exceptions: mileage, etc.
9. When words end in ce or ge the final e is retained before added terminations beginning with a or o: e.g., change, changeable; courage, courageous.
10. In participles the final e is sometimes retained for the purpose of distinguishing them from other words pronounced the same but having a different meaning: e.g., singe, singeing, to distinguish from singing; dye, dyeing, to distinguish from dying, etc. The e is also retained in hoeing, toeing, and shoeing.[3]
11. Words ending in ie change their termination to y upon adding ing: e.g., die, dying; vie, vying.
12. Words ending in y preceded by a consonant change the y to i before any added termination not beginning with i: e.g., {36} merry, merriment; happy, happiness. Exceptions: adjectives of one syllable: e.g., dry, dryly; sly, slyness. Also except derivatives formed by adding ship and hood: e.g., suretyship, babyhood; but hardihood.
When the final y is preceded by a vowel, the y is usually changed to i: e.g., gay, gaiety; day, daily; pay, paid; lay, laid, etc.
13. The French ending -re in theater, center, meager, sepulcher, etc., is not now generally considered good usage.
14. The possessive of proper nouns ending in s or other sibilant is formed by adding the apostrophe and s if the word is of one syllable: e.g., James’s apple; but add the apostrophe alone if the word is of more than one syllable: e.g., For Jesus’ sake.[4]
15. Words which in their shortest form end in -d, -de, -ge, -mit, -rt, -se, -ss take the ending -sion: e.g., abscind, abscission; seclude, seclusion; emerge, emersion; admit, admission; revert, reversion; confuse, confusion; impress, impression. Other words take the ending -tion.[5]