Obama failed to say the word "genocide" on the 95th anniversary of Armenian Remembrance Day, the day in which Armenians mourn for the 1.5 million Armenians who were murdered by the Turkish Muslim Empire, commonly referred to as the Ottoman Empire.
The Armenian "Holocaust," (Armenians and Jews both use the word "Holocaust" when referring to the mass genocidal slaughter of their ancestors) was a mass genocide, and will remain so historically, in spite of Obama's failure to say the word "genocide," favoring the words "Meds Yeghern" or "Great Catastrophe" instead.
Even though Obama called this mass slaughtering of Armenians "one of the worst atrocities of the 20th century,"  he just could not seem to get the word "genocide" to proceed from his brain to his lips, via his speech on behalf of the Armenian people on Armenian Remembrance Day, April 24, 2010.
Obama has a habit of choosing to use cleverly disguised words in his public statements, words he considers to be politically incorrect. For example, Obama seems to have a serious problem in using words related to terrorism, or terrorists, especially if those terrorist happen to be violent fanatical Muslim practitioners of Islam, i.e, Islamic Jihad terrorists. In the particular case of Armenian Remembrance Day, Obama did not wish to offend Turkey, Turkish leaders, or the Turkish government.
"Obama's use of Meds Yeghern "is an elegant dodge to avoid using the 'g-word' -- but the substance of what he states about what happened gives no comfort to those who cling to the Turkish official version," says Harvard University's Andras Riedlmayer. "1.5 million Armenians were rounded up and massacred or marched to their death. Despite the passive construction, that assumes intentionality." 
"Nevertheless, such nuance was not appreciated by the Armenian American lobby group, the Armenian National Committee of America (ANCA), which rapped Obama for 'disgraceful capitulation to Turkey's threats' and of 'offering euphemisms and evasive terminology to characterize this crime against humanity,' in a press release Saturday." 
 Statement of President Barack Obama
on Armenian Remembrance Day
 Obama on Armenian Remembrance Day:
"One of worst atrocities in 20th century"
April 24, 2010
Obama again failed to honour his campaign pledge: ANCA
Frequently Asked Questions About the Armenian Genocide
Encyclopedia of the Middle East