The word came into English in the early 1700s most directly from the Malay word 'kechap', meaning a smooth, thick sauce. However, there may be a link further back from there to the dialect Chinese word 'ketsiap', which was a form of pickled fish.
Although historically there have been many kinds of fruits used for ketchups,
The tomato ketchup that we are familiar with today is based on the recipe that the Brothers Heinz used in their "traveling medicine show". It was offered as a cure-all tonic, but people began using it as a condiment.
I'll try and find an internet source for you to verify with .
Please forgive. I found a much older and clearer history here: http://mimi.essortment.com/historyketchup_rlju.htm
The Highlights: Previous ketchups recipes have been for anchovies or mushrooms or walnuts.
HISTORY OF TOMATO KETCHUP:
1812 first tomato recipe appears in a cookbook
New England farmer sold bottles in 1830
1837 Jonas Yerkes sold it nationwide
1848 some manufacturers were busted for adding funky stuff
by 1900 there were 100 manufactureres of ketchup.
Biggest success came in 1872, when HJ Heinz added ketchup to his line of products