The original language of Japan, or at least the original language of a certain population that was ancestral to a significant portion of the historical and present Japanese nation, was the so-called yamato kotoba (大和言葉 or infrequently 大和詞, i.e. "Yamato words"), which in scholarly contexts is sometimes referred to as wa-go (和語 or rarely 倭語, i.e. the "Wa words"). In addition to words from this original language, present-day Japanese includes a great number of words that were either borrowed from Chinese or constructed from Chinese roots following Chinese patterns. These words, known as kango (漢語), entered the language from the fifth century onwards via contact with Chinese culture. According to a Japanese dictionary Shinsen-kokugojiten (新選国語辞典), Chinese-based words comprise 49.1% of the total vocabulary, Wago is 33.8% and other foreign words are 8.8%.
Like Latin-derived words in English, kango words typically are perceived as somewhat formal or academic compared to equivalent Yamato words. Indeed, it is generally fair to say that an English word derived from Latin/French roots typically corresponds to a Sino-Japanese word in Japanese, whereas a simpler Anglo-Saxon word would best be translated by a Yamato equivalent.
A much smaller number of words has been borrowed from Korean and Ainu. Japan has also borrowed a number of words from other languages, particularly ones of European extraction, which are called gairaigo. This began with borrowings from Portuguese in the 16th century, followed by borrowing from Dutch during Japan's long isolation of the Edo period. With the Meiji Restoration and the reopening of Japan in the 19th century, borrowing occurred from German, French and English. Currently, words of English origin are the most commonly borrowed.
In the Meiji era, the Japanese also coined many neologisms using Chinese roots and morphology to translate Western concepts. The Chinese and Koreans imported many of these pseudo-Chinese words into Chinese, Korean, and Vietnamese via their kanji in the late 19th and early 20th centuries. For example, 政治 seiji ("politics"), and 化学 kagaku ("chemistry") are words derived from Chinese roots that were first created and used by the Japanese, and only later borrowed into Chinese and other East Asian languages. As a result, Japanese, Chinese, Korean, and Vietnamese share a large common corpus of vocabulary in the same way a large number of Greek- and Latin-derived words are shared among modern European languages, although many academic words formed from such roots were certainly coined by native speakers of other languages, such as English.
In the past few decades, wasei-eigo (made-in-Japan English) has become a prominent phenomenon. Words such as wanpatān ワンパターン (< one + pattern, "to be in a rut", "to have a one-track mind") and sukinshippu スキンシップ (< skin + -ship, "physical contact"), although coined by compounding English roots, are nonsensical in most non-Japanese contexts; exceptions exist in nearby languages such as Korean however, which often use words such as skinship and rimokon (remote control) in the same way as in Japanese.
Additionally, many native Japanese words have become commonplace in English, due to the popularity of many Japanese cultural exports. Words such as futon, haiku, judo, kamikaze, karaoke, karate, ninja, origami, rickshaw (from 人力車 jinrikisha), samurai, sayonara, sudoku, sumo, sushi, tsunami, tycoon and many others have become part of the English language. See list of English words of Japanese origin for more.
source : wikipedia