The fact that the perpetrator of the shootings at Parliament Hill in Ottawa had converted to Islam doesn't inherently make him a terrorist. Neither does the fact that you can point to lots of people on Twitter and say "look how scared they were yesterday!" (by that measure, lots of Fox News television journalists would be perpetrating acts of terrorism whenever they talk about Ebola these days). That's because terrorism is about intent.
The fact that he was an addict and possibly mentally ill doesn't make him not a terrorist, either, at least not inherently, and neither does the fact that he wasn't part of an organized group. The fact that he was Canadian-born certainly doesn't make him not a terrorist. That's because terrorism IS ABOUT INTENT, not religious affiliation, not birthplace, not mental status.
How do you show intent? Well, the way we tend to do that in this day and age is for a group that has already talked about its intent to take responsibility for the acts. But an individual could also show terrorist attent by having a manifesto stashed away somewhere (they didn't use the word at the time, but the Unabomber? totally a terrorist).
In the case of the Parliament Hill shootings, we know that the perpetrator attended a mosque in Vancouver, where they were wary of him because of his erratic behaviour, but tried to help him anyway. We know he had a history of drug addiction and had spent some time homeless. We know he had perpetrated earlier crimes in an attempt to get himself locked up. We know that he was not close to his family, and didn't seem to have any friends. We know that the people who knew him at his mosque didn't think he had become "radicalized."
What we don't know (yet?) is why he shot a soldier at the War Memorial yesterday and then went on shooting in various other Parliament Hill buildings. Maybe he was a terrorist, maybe he wasn't. I'm leaning toward "wasn't," myself, but I simply don't know yet--and you don't either. And in the absence of that knowledge, tossing around words like 'terrorism' is both potentially quite incorrect and an action that has the potential to cause a lot of damage.