Rule 7 - adding suffixes
If a noun, adjective or verb ends in y after a consonant, the y is changed to i before adding a suffix. -ful, -ness, -less, ous, -al, -ly, -ed, -er or -est
Examples:
| beauty | beautiful | happy | happiness | mercy | merciless |
| industry | industrial | bury | burial | day | daily |
| heavy | heavier | glory | glorious | certify | certified |
| lonely | loneliest |
