Celtic manager Brendan Rodgers paid tribute to his "infrangibles" after they finished the Ladbrokes Premiership campaign unbeaten with a 2-0 victory over Hearts.
A run of 34 victories and four draws sealed a record 106-point tally as Celtic won their sixth title in a row.
Second-half goals from Leigh Griffiths and Stuart Armstrong sealed a fitting end to the Hoops' dominant league season before they lifted the trophy at Parkhead.
Rodgers has generally avoided talking about the prospect of going a Scottish league campaign unbeaten for the first time since both Celtic and Rangers did so in the late 1890s, but it played a central part in his team talk.
"The word I said to them was infrangible," he said. "That was the word I wrote up on the paper.
"Stuart Armstrong understood it but I did actually say, 'for those of you who don't understand I wrote the meaning below'. So 'to be unbroken', that is another word for their vocabulary."
Rodgers added: "It hasn't really been a key feature up until probably Thursday night. Because there are so many things that are out of our control in this type of situation.
"But the players had arrived with a couple of games to go and then it's real, you can't hide from it. You have a chance to go through a whole season and not be beaten.
"But it's how we did it. The level of football, the tactical discipline and excitement they have given supporters has been incredible to watch. And they now stand alone in history."
The 44-year-old, whose side scored 106 goals, added: "You only have to look at the past, 100 years or so since it was done in the 1890s, to tell you the difficulty of achieving that.
"It's a monumental achievement by the players and I think what gets lost in all the records and everything that is set, there is a real dedication to excellence they have shown since I have come in, in their life, how they have worked hard every day.
"They will probably tell you themselves, they get pushed very, very hard, and hopefully they see the benefits.
"It's a remarkable achievement for the football club and for this group of players and they will scribe their name into the history of this incredible club now. It's something for their kids and grandkids to be proud of."
The former Liverpool manager hit out at critics of Scottish football who claim Celtic's run is down to the poor competition. The Hoops won the league by 30 points from Aberdeen, who set their own record tally.
"It's very unfair, because it's all relative," Rodgers said. "I was at Chelsea when Chelsea beat Wigan 8-0 in the last game of the season to pick up a title. It's a brilliant league but they won 8-0, so what does that make the Premier League?
"The only thing Celtic is missing is money. This is one of the great clubs in the world but it's not in a league where you have the finances. If Celtic had the finances of another league, this thing would just explode because of the sheer size of it."
CELTIC: Gordon, Gamboa (Rogic, 46 mins), Simunovic (Toure, 74 mins), Boyata, Tierney, Brown, Armstrong (Sviatchenko, 78 mins), Roberts, McGregor, Sinclair, Griffiths. Unused subs: De Vries, Bitton, Forrest, Kouassi.
HEARTS: Noring, Brandon, Nowak, Bauben (Walker, 65 mins), Hughes, Smith, Cowie, Tzoli (Henderson, 78 mins), Djoum, Gonvcalves (Martin, 55 mins), Johnsen. Unused subs: Hamilton, Kitchen, Avionitis, Choulay
Referee: John Beaton
Man of the Match: Patrick Roberts
Match rating: 7/10