[first and foremost] {adv. phr.} As the most important thing; first. […]

[first and last] {adv. phr.} Most noticeably; all the time; chiefly. […]

[first of all] {adv. phr.} Chiefly; primarily; as the first thing. […]

[first off] {adv. phr.}, {informal} Before anything else; first. * /First […]

[first thing off the bat] {adv. phr.} Immediately; at once. * […]

[first-class] (2) {adv.} With the best material; in the best or […]

[fit to be tied] (2) {adv. phr.}, {substandard} Very hard. - […]

[flat-out] {adv. phr.}, {informal} 1. Without hiding anything; plainly; openly. * […]

[fifty-fifty] (1) {adv.}, {informal} Equally; evenly. * /The two boys divided […]

[for a song] {adv. phr.}, {informal} At a low price; for […]