adamant　hard; inflexible
adapt make or become suitable for a specific use; alter; modify; adjust; N. adaptation: act of adapting; composition recast into a new form; Ex. The play is an everbuying adaption of a short novel.
addendum addition; appendix to book; something that is added (as at the end of a speech or book)
addiction compulsive habitual need
addle　make or become confused; muddle; drive crazy; become rotten (egg)
address direct a speech to; speak to; deal with or discuss; direct one's efforts or attention to; make with a destination; N: formal speech