Tip: See my list of the 
MostThis article will teach you how to say (or rather write) “Merry Christmas” in more than 100 different languages. The languages are grouped by the continents where they are widely spoken (some of the languages are mentioned several times).
I have also made a map for European languages, which shows the geographical distribution of the European expressions.
European languages
Albanian: Gëzuar Krishtlindja
Aragonese: Feliz nadal
Armenian: շնորհավոր Սուրբ Ծնունդ (šnorhavor Surb Cnund)
Asturian: Feliz navidá
Azerbaijani: Xoşbəxt milad
Basque: Eguberri on
Belarusian: з Калядаамі (z Kaljadámi), з Нараджэннем (z Naradžénnjem), з Нараджэннем Хрыстовым (z Naradžénnjem Xrystóvym)
Bosnian: Srećan Božić, Sretan Božić
Breton: Nedeleg laouen
Bulgarian: Весела Коледа (Vesela Koleda)
Catalan: Bon Nadal
Cornish: Nadelik Lowen
Corsican: Bon Natale è pace è salute
Croatian: Sretan Božić
Czech: Veselé Vánoce
Danish: glædelig jul, god jul
Dutch: Vrolijk kerstfeest, prettig kerstfeest
English: Merry Christmas, Happy Christmas
Esperanto: Ĝojan Kristnaskon
Estonian: Häid jõule
Faroese: Gleðilig jól
Finnish: Hyvää joulua, Hauskaa joulua
French: Joyeux Noël
Frisian (West): Noflike krystdagen
Galician: Bo Nadal
Georgian: შობას გილოცავთ (šobas gilocavt)
German: Frohe Weihnachten, Fröhliche Weihnachten
Greek: Καλά Χριστούγεννα (kalá Christoúgenna)
Greenlandic: Juullimi pilluarit, Juullisiorluarit
Hungarian: Boldog karácsonyt
Icelandic: Gleðileg jól
Irish: Nollaig Shona
Italian: Buon Natale
Latin: Felix dies Nativitatis, Natale Hilare
Latvian: Priecīgus Ziemassvētkus
Lithuanian: Linksmų Kalėdų
Luxembourgish: Schéine Chrëschtdag
Macedonian: Среќен Божиќ (Sreḱen Božiḱ), Христос се роди (Hristos se rodi), Навистина се роди (Navistina se rodi) (reply to “Hristos se rodi”)
Maltese: il-Milied it-Tajjeb
Moksha: Роштува мархта (Roštuva marxta)
Norman: Un bouan Noué (Jersey)
Norwegian: god jul
Occitan: Bon Nadal
Polish: Wesołych Świąt, Wesołych Świąt Bożego Narodzenia
Portuguese: Feliz Natal
Romanian: Crăciun fericit
Russian: с Рождеством (s Roždestvóm), с Рождеством Христовым (s Roždestvóm Xristóvym), Весёлого Рождестваа (Vesjólovo Roždestvá), Счастливого Рождестваа (Sčastlívovo Roždestvá)
Sami (Lule): Buorre javla
Sami (Northern): Buorit juovllat
Sami (Southern): Buerie jåvle
Sardinian: Bona Pasca de Nadale
Scottish Gaelic: Nollaig Chridheil
Serbian: Срећан Божић (Srećan Božić), Сретан Божић (Sretan Božić), Христос се роди (Hristos se rodi), Ваистину се роди Vaistinu se rodi (reply to “Hristos se rodi”)
Silesian: Radosnych Godōw
Slovak: Veselé Vianoce
Slovene: Vesel božič
Sorbian (Lower): Wjasołe gódy
Sorbian (Upper): Wjesołe hody
Spanish: feliz Navidad
Swedish: God jul
Turkish: Mutlu Noeller
Ukrainian: з Різдвом (z Rizdvóm), з Різдвом Христовим (z Rizdvóm Xrystóvym)
Welsh: Nadolig Llawen
Yiddish: אַ פֿריילעכן ניטל (a freylekhn nitl)
Asian languages
Arabic: عِيد مِيلَاد مَجِيد (ʿīd mīlād majīd), مِيلَاد مَجِيد (mīlād majīd)
Armenian: շնորհավոր Սուրբ Ծնունդ (šnorhavor Surb Cnund)
Azerbaijani: xoşbəxt milad
Burmese: Hnit thit ku mingalar pa
Cebuano: Malipayong pasko
Chinese (Mandarin): 聖誕快樂, 圣诞快乐 (Shèngdàn kuàilè), 聖誕節快樂, 圣诞节快乐 (Shèngdànjié kuàilè)
Georgian: შობას გილოცავთ (šobas gilocavt)
French: Joyeux Noël
Hebrew: חג מולד שמח (khag molad sameakh)
Hindi: शुभ बड़ा दिन (śubh baṛā din), शुभ क्रिस्मस (śubh krismas), मेरी क्रिसमस (merī krismas), क्रिसमस मुबारक (krismas mubārak)
Indonesian: selamat hari Natal, selamat Natal
Japanese: メリークリスマス (Meri Kurisumasu)
Javanese: Sugeng Natal
Jingpho: Ngwi pyaw ai X’mas rai u ga
Karo Batak: Selamat wari Natal
Kazakh: рождество құтты болсын (rojdestvo quttı bolsın)
Khmer: រីករាយថ្ងៃបុណ្យណូអែល (riikriəythngaybonyɔɔnouʾael), បុណ្យណូអែល (bon-nouʾael)
Korean: 즐거운 성탄절 (jeulgeoun seongtanjeol), 메리 크리스마스 (meri keuriseumaseu)
Kyrgyz: Жаратканнын туысымен (Caratkannın tuısımen)
Lao: ສຸກສັນວັນຄຣິດສມາດ (suk san wan kha rit sa māt)
Malay: Selamat hari Natal, selamat Natal
Mongolian: Зул сарын мэнд хүргэе (Zul saryn mend hürgeje)
Persian: میلاد مسیح مبارک باد (milâd-e masih mobârak bâd), کریسمس مبارک (kerismas mobârak)
Sinhalese: සුභ නත්තලක් (subha nattalak)
Sundanese: Wilujeng Natal
Tagalog: Maligayang pasko
Tajik: Мавлуди Исо муборак (mavludi Iso muborak)
Tamil: கிறிஸ்துமஸ் நல்வாழ்த்துக்கள் (kiṟistumas nalvāḻttukkaḷ)
Telugu: మెర్రీ క్రిస్మస్ (merrī krismas)
Thai: สุขสันต์วันคริสต์มาส (sùk-sǎn wan krís-mâas)
Turkish: Mutlu Noeller
Urdu: کرسمس مبارک (krismas mubārak), میری کرسمس (merī krismas), شبھ کرسمس (shubh krismas), شبھ بڑا دن (shubh baṛā din)
Uzbek: Rojdestvo muborak
Vietnamese: Chúc mừng Giáng sinh, Chúc mừng Nô-en, Chức mừng Giáng sinh, Chức mừng Nô-en
African languages
Afrikaans: Geseënde kersfees
Akan: Afishapa
Amharic: መልካም ገና (mälkam gäna)
Arabic: عِيد مِيلَاد مَجِيد (ʿīd mīlād majīd), مِيلَاد مَجِيد (mīlād majīd)
Chichewa: khrisimasi yabwino
English: Merry Christmas, Happy Christmas
Ewe: Blunya na wo
French: Joyeux Noël
Portuguese: Feliz Natal
Swahili: Heri ya Krismasi, Krismasi njema
Zulu: uKhisimusi oMuhle
American languages
Alutiiq: Nunaniqsaakici Aʀusistuami
Aymara: Sooma nawira-ra
Cherokee: ᎤᏬᏢᏗ ᏓᏂᏍᏓᏲᎯᎲ (uwotlvdi danisdayohihv)
English: Merry Christmas
Greenlandic: Juullimi pilluarit, juullisiorluarit
Haitian Creole: Jwaye Nowèl
Hawaiian: Mele Kalikimaka
Lushootseed: Haʔɬ pədx̌aʔx̌aʔ
Navajo: Yáʼátʼééh Késhmish, Nizhónígo Késhmish Adííłeeł
Papiamentu: Bon Pascu
Portuguese: Feliz Natal
Spanish: Feliz Navidad
Yup’ik: Alussistuaqegtaarmek piamken, Alussistuaqegcikici (plural subject, plural object)
Languages of Oceania
English: Merry Christmas, Happy Christmas
Samoan: Manuia le Kerisimasi
