Tharoor's tweet came shortly after Modi, while speaking via video conference, said on Friday that "we can simply start with publishing one word in 10-12 different languages spoken across the country".
"In a year, a person can learn over 300 new words in different languages," the Prime Minister added.
Responding to Modi's word challenge, Tharoor, who is known for his witty words, in a series of tweets said: "Prime Minister Narendra Modi ended his speech at the Manorama News Conclave by suggesting we all learn one new word a day from an Indian language other than our own. I welcome this departure from Hindi dominance and gladly take him up on this language challenge.
"In response to the Prime Minister's language challenge, I will tweet a word daily in English, Hindi and Malayalam. Others can do this in other languages. Here is the 1st one: Pluralism (English), 'bahulavaad' (Hindi), 'bahuvachanam' (Malayalam)."
An hour later, Tharoor also suggested two more meanings of pluralism in Malayalam, saying: "Ok here's part of my language challenge: there are often better options for a particular word. Pluralism is better translated in Malayalam ('bahuswarata', many voices) than as (many things)."
Tharoor has on number of occasion sent twitterati to consult the dictionary with his choice of words.
Tharoor recently while tweeting in support of former Finance Minister P. Chidambaram said: " It is a tribute to your strength of character that you are standing up to persecution and character assassination with courage and confidence. I believe justice will prevail in the end. Till then we will have to allow some malicious minds their schadenfreude."
Schadenfreude means a feeling of pleasure at the bad things that happen to other people.
Tharoor has in the past used words like "farrago", "rodomontade", "webaqoof", "kakistocracy" and "snollygoster".
( With inputs from IANS )