unable

Etymology 1

From Middle English unable, unabel, unhable, unhabil, equivalent to un- + able.

adj

1. Not able; lacking a certain ability.
   Are you unable to mind your own business or something?
   Fulham switched off as Giggs took a quick corner to Valencia. He played it back to Giggs, whose cross was headed in by Nani with the lurking Rooney unable to add a touch. December 21, 2011, Tom Rostance, “Fulham 0-5 Man Utd”, in BBC Sport
   Seeing the British establishment struggle with the financial sector is like watching an alcoholic […]. Until 2008 there was denial over what finance had become. […] But the scandals kept coming, […]. A broad section of the political class now recognises the need for change but remains unable to see the necessity of a fundamental overhaul. 2013-06-28, Joris Luyendijk, “Our banks are out of control”, in The Guardian Weekly, volume 189, number 3, page 21
   The train operating company owning group warned in early December that it was unable to publish its results for the year to July 3 2021, following an investigation into the running of Southeastern, which was stripped of its franchise in October …. January 12 2022, “Network News: Trading of Go-Ahead Group shares halted”, in RAIL, number 948, page 7

intj

1. (aviation) Indicating that a requested course of action is not possible to carry out.
   "November three seven kilo, climb and maintain twelve thousand." "Unable, we have pressurization problems. Maintaining nine thousand."

Etymology 2

From Middle English unablen, equivalent to un- + able.

verb

1. (transitive, nonstandard) To render unable; to disable.