Princeton's WordNet

1. Christianity, Christian religion(noun)

   a monotheistic system of beliefs and practices based on the Old Testament and the teachings of Jesus as embodied in the New Testament and emphasizing the role of Jesus as savior

2. Christendom, Christianity(noun)

   the collective body of Christians throughout the world and history (found predominantly in Europe and the Americas and Australia)

   "for a thousand years the Roman Catholic Church was the principal church of Christendom"

Kernerman English Learner's Dictionary

1. Christianity(noun)ˌkrɪs tʃiˈæn ɪ ti

   a religion based on the belief in Jesus Christ

Wiktionary

1. Christianity(Noun)

   An Abrahamic religion based on the teachings of Jesus Christ and various scholars who wrote the Christian Bible.

Origin: * Respelling of cristente, from crestiente, from stem of christianitas, from christianus

Webster Dictionary

1. Christianity(noun)

   the religion of Christians; the system of doctrines and precepts taught by Christ

2. Christianity(noun)

   practical conformity of one's inward and outward life to the spirit of the Christian religion

3. Christianity(noun)

   the body of Christian believers

The Nuttall Encyclopedia

1. Christianity

   Belief (q. v.) that there is in Christ, as in no other, from first to last a living incarnation, a flesh and blood embodiment, for salvation of the ever-living spirit of the ever-living God and Father of man, and except that by eating His flesh and drinking His blood, that is, except by participating in His divine-human life, or except in His spirit, there is no assurance of life everlasting to any man; but perhaps it has never been defined all round with greater brevity and precision than it is by Ruskin in his "Præterita," under the impression that the time is come when one should say a firm word concerning it: "The total meaning of it," he says, "was, and is, that the God who made earth and its creatures, took, at a certain time upon the earth, the flesh and form of man; in that flesh sustained the pain and died the death of the creature He had made; rose again after death into glorious human life, and when the date of the human race is ended, will return in visible human form, and render to every mail according to his work. Christianity is the belief in, and love of, God thus manifested. Anything less than this," he adds, "the mere acceptance of the sayings of Christ, or assertion of any less than divine power in His Being, may be, for aught I know, enough for virtue, peace, and safety; but they do not make people Christians, or enable them to understand the heart of the simplest believer in the old doctrine."

U.S. National Library of Medicine

1. Christianity

   The religion stemming from the life, teachings, and death of Jesus Christ: the religion that believes in God as the Father Almighty who works redemptively through the Holy Spirit for men's salvation and that affirms Jesus Christ as Lord and Savior who proclaimed to man the gospel of salvation. (From Webster, 3d ed)

• ChristenskapAfrikaans
• المَسيحِيَّه، النَّصْرانِيَّهArabic
• християнствоBulgarian
• cristianismoPortuguese (BR)
• křesťanstvíCzech
• das ChristentumGerman
• kristendomDanish
• χριστιανισμόςGreek
• cristianismoSpanish
• ristiuskEstonian
• دین مسیحFarsi
• kristinuskoFinnish
• christianismeFrench
• נַצרוּתHebrew
• ईसाई धर्मHindi
• kršćanstvo, kršćanska vjeraCroatian
• kereszténységHungarian
• agama KristenIndonesian
• kristni, kristin trúIcelandic
• cristianesimo, cristianitàItalian
• キリスト教Japanese
• 기독교Korean
• krikščionybėLithuanian
• kristietībaLatvian
• agama KristianMalay
• christendomDutch
• kristendom, kristenhetNorwegian
• chrześcijaństwoPolish
• دین مسیحPersian
• د عیسوی دینPashto
• cristianismoPortuguese
• creştinismRomanian
• христианствоRussian
• kresťanstvoSlovak
• krščanstvoSlovenian
• hrišćanstvoSerbian
• kristendom[en], den kristna läranSwedish
• ศาสนาคริสต์Thai
• HristiyanlıkTurkish
• 基督教Chinese (Trad.)
• християнствоUkrainian
• عیسائیتUrdu
• đạo Cơ đốcVietnamese
• 基督教Chinese (Simp.)