The word agile literally means being nimble or have the ability to move quickly and easily. This is how dictionary.com defines it and honestly this is the crux of it.
Everything else we hear
Frameworks: scrum, kanban, SAFe, LeSS, DaD, Nexus, etc...
Practices: XP, RAD, test automation, continuous integration (CI), continuous deployment, etc...
Tools: puppet, docker, jira, amazon web services (aws), etc...
Structure: feature team, etc...
Devops
support your quest towards agility but by themselves are not agile.
I prefer to relate to them as design patterns (anyone with a technology background will know what I'm talking about, for those who don't please refer to this link). In simplified terms it means "someone somewhere applied a set of techniques or patterns to solve a commonly occurring problem which turned out to be reusable given a similar context and structure".
Please use these design patterns to solve your problems and do not get stuck with 1 definition of agile.
So what is it really. I present to you the most shared picture in the agile world (not sure who created the original version of this picture but high five to you mate):
You must have the right mindset (will be writing an article on the agile mindset) and be guided by values and principles and supported by the abovementioned "design principles" to achieve the level of agility that you've been working towards. I'm personally not a big fan of the doing agile part. It makes agile sound like a framework. Neither am I a big fan of the word "Agile". That sounds like the name of a framework. As the definition above states - it's an adjective. That's why I added the "not Agile" in the title. It's not the name of a person, place or thing. It's a way of working (WoW).
There's a lot of myths about agile (feel free to read my article on these myths). A popular myth about agile is that it's only for software development and these techniques can only be used in certain projects. Well neither of those is true. You can apply the above "design patterns" to any industry or domain and to any project as long as we do not lose the ethos of the values and principles. Don't believe me - check out the below video on how a car was built in an agile way:
Would love to hear your definition of agility. Believe me it doesn't matter if you're certified or not or have experience or not. If you're consistently delivering as per your customer's expectations with the highest possible quality and always finding ways to improve on that, then you're agile as you're infusing more and more agility into your work / business as you progress.
Happy days and happy sharing and learning :)