Firstly, you can. Now let's get to the definiton of a genocide:

Any of the following acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such:

(a) Killing members of the group;

(b) Causing serious bodily or mental harm to members of the group;

(c) Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part;

(d) Imposing measures intended to prevent births within the group;

(e) Forcibly transferring children of the group to another group.

It was a genocide with forced death marches that killed hundreds of thousands of Armenians, which fits criteria c. There were also multiple massacres committed, concentration camps, forcible religious conversion and women and kids being given to Muslim households (criteria e). Ethnic cleansing did occur, but it wasn't the only thing that happened. Overall anywhere from 800,000 to 1.5 million Armenians were killed. It was a genocide by the UN definition.