first

Concise Oxford English Dictionary © 2008 Oxford University Press:
first/fɜːst/

▶ordinal number

• 1 coming before all others in time or order; earliest; 1st.

  ■ before doing something else.

• 2 foremost in position, rank, or importance.

  ■ Brit. a place in the top grade in an examination for a degree.

• 3 for the first time.

  ■ informal something never previously occurring or done.

• 4 with a specified part or person in a leading position: the car plunged nose first into the river.

• 5 Music performing the highest or chief of two or more parts for the same instrument or voice.

– phrases
at first at the beginning.
first and foremost more than anything else.
first and last fundamentally.
first of all before doing anything else.

■ most importantly.

first off informal as a first point; firstly.
first past the post winning a race by being the first to reach the finishing line.

■ Brit. denoting an electoral system in which a candidate or party is selected by achievement of a simple majority.

first thing early in the morning; before anything else.
first up informal first of all.
in the first place as the first consideration or point.

■ to begin with.

of the first order (or magnitude) excellent or considerable of its kind.

– origin OE fyr(e)st; of Gmc origin.