Constant is an adjective that describes something or someone as unchanging, loyal, or happening all the time. The adverb form is constantly. The noun form is constancy.
It comes from the Latin constare, which means to stand.
Consistent is also an adjective. It describes something or someone as continuing to happen, continuing to behave in the same manner, or continuing to have the same quality with each use. The adverb form is consistently. The noun form is consistency.
It comes from the Latin consistere, which oddly means to stop or stand still.
The Latin word sistere is similar to stare. So these words have been close cousins since the sixteenth century, but never the same word.
In short, something is constant if it does not stop, though it may vary. Consistent things may start and stop, but do not vary.
Another point that should be kept in mind is that this engagement with stakeholders needs to be constant and on-going instead of companies jumping onto the social media bandwagon when something goes wrong! [Forbes India]
Utah’s colleges are “constantly under attack,” said David Buhler, state higher education commissioner. “We don’t want to be the next one on the list with a major breach in our system.” [The Salt Lake Tribune]
“They’re sitting at 7-3, so they’re a very consistent team, they play at a certain level and you’ve got to play better at that level to beat them because they’re not going to drop off and have a bad game. If we had that same consistency, we’d be 7-3 also, but we’re sitting just the opposite of that and looking up at them.” [HJ News]
They’ve consistently been one of the most underrated lines in the league for a few years and this year have the added bonus of being followed by a solid second line, driven by another underrated player in Mathieu Perreault, that is generating plenty of goals. [Winnepeg Sun]