This is a Fedora 28 rawhide system. This problem has been happening since Fedora 27 rawhide.
Check which key bindings is selected in Settings -> Edit Current Profile -> Keyboard, "Default (XFree 4)" has the ctrl+right/left behaviour you describe out-of-the-box.
Ahmad, You're absolutely correct. I made the change a few weeks ago... several times in an attempt to resolve the problem but had NO luck. Does this mean that the other two "terms" are broken? ctrl-rightarrow works there but NOT ctrl-leftarrow. You are the man! Could I get you to take a peek at this bug please? https://bugzilla.mozilla.org/show_bug.cgi?id=1381255 THANKS! George..
The other two key bindings are not broken; if you're using bash, check /etc/inputrc, the key bindings defined there for "forward-word" and "backward-word" should correspond to the key bindings (or escape sequences) that are produced by konsole when you press those keys.