I am so glad you posted a few times after me since this will show everyone your standard mode of operation. You use a word that already has an established definition and use the "abstract" definition (aka you'll make it up).
In fact if you go to the chord
WP page, you'll notice that there isn't the word "abstract" anywhere on the page. Same thing with Chord_(geometry)
WP and Chord_(graph_theory)
WP.
You had the chance to define what you mean by "abstract" when I called upon the fact that there is no abstract definition. Funny that you decided to give us two standard definitions that show chords are not "a line segment that is straight or not".
Generally speaking, it's a line segment that connects two points on a circle's circumference. A diameter is a special chord, just like a square is a special rectangle. Nothing abstract about chords there.
Love is abstract, hate is abstract, Picasso is abstract. And my 10 minutes are up for this post.