first class 
noun [in singular]
1A set of people or things grouped together as the best: the first class of the orders of chivalry
1.1 [mass noun] The best and most expensive seating or accommodation in a train, aircraft, or ship: a seat in first class
adjective & adverb
1Of the best quality or in the highest division: [as adjective]: the hotel offers first-class accommodation...
- One of the driving forces behind Advancing Together, the region's strategic framework, is the need to provide a first-class quality of life for everyone and be intolerant of discrimination.
- The children of Ballou deserve a chance at the first-class quality of education Whitman students receive.
- Although the 1st Infantry Division was a first-class unit, it did suffer the occasional bad officer.
Synonyms
superior, first-rate, high-quality, top-quality, top, top-tier, quality, high-grade, five-star, fine;
prime, premier, premium, grade A, best, finest, select, of the first water;
exclusive, elite, special;
excellent, exceptional, exemplary, superlative, superb;
British top of the range;
chiefly US top of the line;
French par excellence
informal tip-top, A1, top-notch, stellar, plum
1.1Relating to the best seating or accommodation in a train, aircraft, or ship: [as adjective]: a first-class carriage [as adverb]: you can travel first class on any train...
- It was laid out in the style of a first-class train carriage.
- We had arrived in the morning by a first-class - only train - Abela - from Cairo.
- Posing as a QC, he boarded the first-class carriage of an Edinburgh-bound Virgin train and complained his wallet and laptop had been stolen.
1.2Relating to a class of mail given priority: [as adjective]: first-class mail [as adverb]: send it first class...
- If we see any evidence of first-class mail being treated as second class we will take it very seriously, investigate and take all necessary action.
- A postal survey carried out by the Evening Advertiser has shown that most first-class mail sent out from Swindon reaches its destination on time.
- Postal bosses have been set a minimum national target of 92.5 per cent of first-class mail being delivered the next working day.
1.3British Relating to the highest division in the results of a university examination: a first-class honours degree...
- He spoke four languages and had a first-class degree from the University of London.
- At the University of Sydney he carried off prizes, graduated with first-class honours in classics, and played cricket with enthusiasm.
- Morgan returned to Glasgow University in 1946 and graduated with first-class honours in English Language and Literature in 1947.
1.4 [as adjective] (Of cricket) played between sides of recognized stature and with matches of two innings per side.It has never hosted a first-class cricket match....
- Fulton's hundred, his fourth in first-class cricket, was continuing evidence of his growing stature as a batsman for the future.
- Incidentally, that was also my first wicket in first-class cricket.