Merriam-Webster Collegiate Dictionary - faithful

 I. adjective  Date: 14th century  1. obsolete full of faith  2. steadfast in affection or allegiance ; loyal  3. firm in adherence to promises or in observance of duty ; conscientious  4. given with strong assurance ; binding a ~ promise  5. true to the facts, to a standard, or to an original a ~ copy  • ~ly adverb  • ~ness noun Synonyms:  ~, loyal, constant, staunch, steadfast, resolute mean firm in adherence to whatever one owes allegiance. ~ implies unswerving adherence to a person or thing or to the oath or promise by which a tie was contracted ~ to her promise. loyal implies a firm resistance to any temptation to desert or betray remained loyal to the czar. constant stresses continuing firmness of emotional attachment without necessarily implying strict obedience to promises or vows constant friends. staunch suggests fortitude and resolution in adherence and imperviousness to influences that would weaken it a staunch defender of free speech. steadfast implies a steady and unwavering course in love, allegiance, or conviction steadfast in their support. resolute implies firm determination to adhere to a cause or purpose a resolute ally.  II. noun  Date: circa 1533  1. plural in construction  a. church members in full communion and good standing — used with the  b. the body of believers in Islam — used with the  2. plural ~ or ~s one who is ~; especially a loyal follower, member, or fan party ~s