This English expression is not used as much now as it was in the past but it still constitutes an important part of the English language. If you want to find out more then keep reading!
This expression is used in order to denote that something is definitely dead. It should only be employed when there is no ambiguity regarding the death. The idea behind it is that dodos have been extinct for such a long time that they are all certainly dead and therefore if something is described as “dead as a dodo” then there is no question regarding the death.
The widespread use of this phrase came about after Lewis Carroll used a dodo as one of the characters in his novel Alice’s Adventures in Wonderland in 1865. In his novel he did not use the phrase “as dead as a dodo,” but it is still suggested that using a dodo as a character sparked the use of the phrase itself.
A similar phrase, “as rare as a dodo,” was used in the 1860’s and 70’s but it is not until 1891 in the Bangor Daily Whig And Courier that the first use of the phrase with the word “dead” is found. It reads “after the next general election Mr. Parnell will have only four followers. Except as a private member of Parliament he is as dead as a dodo.”
An example of this expression can be found in a quote from the actress Joan Fontaine. She is quoted to have said “marriage, as an institution, is as dead as the dodo bird.”