“Terminado.” A word that until this week, I had only known from childhood holidays when my old man would try to persuade the barman for “dos cervezas” after closing time at the pool bar.

But it is a word that should send shivers up the spine of every Celtic supporter, and send a lightning bolt up the jacksie of every member of the Celtic board.

It was the term Brendan Rodgers used this week to describe his job at the Scottish champions should the club ever get comfortable and refuse to match his relentless drive for improvement.

With the protracted and ultimately failed wooing of John McGinn, Rodgers’ growing unease at the lack of signings that have arrived at the club this summer bordered into annoyance.

And it has left many wondering if the Celtic manager’s public barbs at his board are an effort to jolt them into life and support his ambitions for the club, or if he is reaching the point where he may consider what would have seemed inconceivable just a few months, if not weeks ago. Namely that he would leave the club he supported as a boy and seemed destined to lead to the holy grail of 10 league titles in a row.

Now, I am not saying I subscribe to that theory, and I would warn against any Rangers supporters setting the cracked Celtic crest as their Twitter profile picture just yet.

But the unease between the manager and the boardroom in terms of what level of investment they feel has to be made in the playing squad this summer has been apparent for quite some time now, and as time drifts on without any of the targets identified by Rodgers and head scout Lee Congerton arriving, the more that grows.

Odsonne Edouard arrived in a transfer-record breaking deal from Paris Saint Germain of course, but the fact that he was already at the club last season on loan and had his £9million transfer fee offset against the £7million departure of Stuart Armstrong, has left the manager and supporters thirsty for fresh blood.

It was over six weeks ago now that Rodgers sat down in Austria with the press and outlined what he felt was an urgent need to replace key players such as Armstrong and Patrick Roberts with players of similar quality, and yet, here we are in the guts of the Champions League qualifying games and only Emilio Izaguirre has since arrived at the club.

The left-back has essentially been signed so that Kieran Tierney can have the odd rest as he continues his development, as well as allowing young Calvin Miller to go out on loan, and so does nothing to address the areas of concern identified by Rodgers.

Australian wonderkid Daniel Arzani will also soon finalise his loan deal, but he is clearly viewed as a work in progress, as is Lewis Morgan who has impressed behind the scenes since joining up with the squad at the start of pre-season.

For me, the area that needed addressed more than any other was the centre of defence. Jack Hendry and Kris Ajer may well develop into top centre-backs, but while 23 and 20 respectively, the point is that they are still developing.

They are going to have lapses now and again, such as the one from Ajer on Wednesday night that helped AEK Athens score and leave Celtic’s hopes of Champions League football in the balance.

You might say that Rodgers isn’t blameless when it comes to failing to address that area. Hendry after all was his own signing, and played ahead of Jozo Simunovic, who sat on the bench during the week. Marvin Compper too is so far out of the picture that he rivals Ashley Cole in that infamous Roma team photo.

But Compper and Hendry hardly broke the bank, and given that Rodgers has delivered the guts of £60million into the club’s coffers in the past two seasons through reaching the Champions League group stages, he was surely entitled the trust to invest a significant amount of that back into the team to ensure they got there for the third time on the bounce.

Would a combination of the board’s failure to back him financially and an exit from the qualifiers on Tuesday night be enough to make Rodgers consider his position? I remain to be convinced.

But what is certain is that the Celtic board are playing a dicey game when it comes to keeping a manager happy who has delivered back-to-back trebles.

If they’re not careful, it might be hasta la vista, Brendan.