The Language of Death

Known for an apprehensiveness towards mentioning death, Japan's use of language is similarly fluid to Western culture in the way that it softens when addressing difficult topics - particularly the loss of life. 

'死/し' is the well-known written form of 'death' to the point people will avoid uttering words with similar sounds (such as 'four/四/し'). 

The following words mean 'death', but are used in different circumstances to soften the impact of the topic.

死にました (しにました)

The direct and most commonly understood word for 'death'; often used coldly or without emotion about anything which has died. It can be a statement of not feeling warmth or a connection to the death, or may be used directly to offend.
Example: A man died here last year. 昨年に、男がここに死にました。

死亡した (しぼうした)

​A softer meaning of death to express a fact or statement. Most commonly used in news reports on television and in written text, this term signifies the sorrowful loss of someone distant or unknown.
Example: Five people died in a car accident. 5人が交通事故で死亡しました。

A news report about a man in his forties or fifties who died in a glider accident.

During Obon, conversations about death are more common as ancestors return to the living. 
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亡くなりました (なくなりました)

Most often used in everyday circumstances, the meaning is similar to 'pass on / passed away'. While traditionally reserved as a polite expression to state someone has died, it is generally used for people or animals which the speaker considered dear.
Example: My grandmother passed away yesterday. 昨日、私のお祖母ちゃんが亡くなりました。

To avoid seeming cold-hearted or cruel, '亡くなりました' is the safest phrase to use in conversation.