In China, the war is most commonly known as the "War of Resistance against Japan" (simplified Chinese: 抗日战争; traditional Chinese: 抗日戰爭), and shortened to the "Resistance against Japan" (Chinese: 抗日) or the "War of Resistance" (simplified Chinese: 抗战; traditional Chinese: 抗戰). It was also called the "Eight Years' War of Resistance" (simplified Chinese: 八年抗战; traditional Chinese: 八年抗戰), but in 2017 the Chinese Ministry of Education issued a directive stating that textbooks were to refer to the war as the "Fourteen Years' War of Resistance" (simplified Chinese: 十四年抗战; traditional Chinese: 十四年抗戰), reflecting a focus on the broader conflict with Japan going back to 1931. It is also referred to as part of the "Global Anti-Fascist War", which is how World War II is perceived by the Communist Party of China and the PRC government.
In Japan, nowadays, the name "Japan–China War" (Japanese: 日中戦爭, romanized: Nitchū Sensō) is most commonly used because of its perceived objectivity. When the invasion of China proper began in earnest in July 1937 near Beijing, the government of Japan used "The North China Incident" (Japanese: 北支事變/華北事變, romanized: Hokushi Jihen/Kahoku Jihen), and with the outbreak of the Battle of Shanghai the following month, it was changed to "The China Incident" (Japanese: 支那事變, romanized: Shina Jihen).
The word "incident" (Japanese: 事變, romanized: jihen) was used by Japan, as neither country had made a formal declaration of war. From the Japanese perspective was that localizing these conflicts was beneficial in preventing intervention from other nations, particularly the United Kingdom and the United States, which were its primary source of petroleum and steel respectively. A formal expression of these conflicts would potentially lead to American embargo in accordance with the Neutrality Acts of the 1930s. In addition, due to China's fractured political status, Japan often claimed that China was no longer a recognizable political entity on which war could be declared.
In Japanese propaganda, the invasion of China became a crusade (Japanese: 聖戦, romanized: seisen), the first step of the "eight corners of the world under one roof" slogan (Japanese: 八紘一宇, romanized: Hakkō ichiu). In 1940, Japanese Prime Minister Fumimaro Konoe launched the Taisei Yokusankai. When both sides formally declared war in December 1941, the name was replaced by "Greater East Asia War" (Japanese: 大東亞戰爭, romanized: Daitōa Sensō).
Although the Japanese government still uses the term "China Incident" in formal documents, the word Shina is considered derogatory by China and therefore the media in Japan often paraphrase with other expressions like "The Japan–China Incident" (Japanese: 日華事變/日支事變, romanized: Nikka Jiken/Nisshi Jiken), which were used by media as early as the 1930s.
The name "Second Sino-Japanese War" is not commonly used in Japan as the war it fought with the Qing dynasty in 1894 is called the Qing-Japanese War (Japanese: 日清戦争, romanized: Nisshin–Sensō) rather than the First Sino-Japanese War.