Từ vựng Tiếng Hàn có khoảng 500,000 từ

here’s a list for 11 of the most spoken languages around the world (sources given as hyperlinks):

LANGUAGE	LARGEST DICTIONARY	NUMBER OF WORDS
Chinese	汉语大词典 (Hanyu Da Cidian. Lit: Comprehensive Chinese Word Dictionary)	370,000 words; 23,000 head Chinese character entries
English	The Second Edition of the 20-volume Oxford English Dictionary	171,476 words in current use, and 47,156 obsolete words; 615,100 definitions
Dutch	Woordenboek der Nederlandsche Taal(Dictionary of the Dutch language)	430,000 words
French	Le Grand Robert de la langue française	100,000 words; 350,000 definitions
German	Der Duden	135,000 words
Italian	Grande dizionario italiano dell’uso (Gradit)	270,000 words
Japanese	(日本国語大辞典)Nihon kokugo daijiten	500,000 words (this includes definitions and etymologies of foreign loan words (gairaigo, 外来語), highly recent words (gendai yōgo, 現代用語), archaic words (kogo, 古語), idiomatic compound  phrases (jukugo, 熟語), words that can  be written using more than one possible Chinese character to produce subtle differences in meaning (dōkun iji, 同訓異字), and Chinese characters that are written differently but have the same pronunciation (iji dōkun, 異字同訓), some slang (ingo, 隠語), and words used only in regional dialects (hōgen, 方言))
Korean	표준국어대사전 (Korean Standard Unabridged Dictionary)	500,000 words (this includes 190,000 technical words (전문어), 70,000 North Korean words (북한어), 20,000 regionalisms (방언), and 12,000 old sayings (옛말))
Russian	Толко́вый слова́рь живо́го великору́сского языка́(Explanatory Dictionary of the Living Great Russian Language; AKA Dahl’s Explanatory Dictionary)	200,000 words
Spanish	Diccionario de la Real Academia Española	100,000 words
Portuguese	Vocabulário Ortográfico da Língua Portuguesa	Nearly 390,000 words

From http://www.lingholic.com/how-many-words-do-i-need-to-know-the-955-rule-in-language-learning-part-2/