Breathe–easy

to take air, oxygen, etc., into the lungs and expel it; inhale and exhale; respire.
(in speech) to control the outgoing breath in producing voice and speech sounds.
to pause, as for breath; take rest:
How about giving me a chance to breathe?
to move gently or blow lightly, as air.
to live; exist:
Hardly a man breathes who has not known great sorrow.
to be redolent of.
(of a material) to allow air and moisture to pass through easily:
The jacket is comfortable because the fabric breathes.
(of the skin) to absorb oxygen and give off perspiration.
(of a wine) to be exposed to air after being uncorked, in order to develop flavor and bouquet.
to inhale and exhale in respiration.
to exhale:
Dragons breathe fire.
to inject as if by breathing; infuse:
She breathed life into the party.
to give utterance to; whisper.
to express; manifest.
to allow to rest or recover breath:
to breathe a horse.
to deprive of breath; tire; exhaust.
to cause to pant; exercise.
breathe down someone’s neck,

to be close to someone in pursuit; menace; threaten:
Police from four states were breathing down his neck.
to watch someone closely so as to supervise or control:
If everyone keeps breathing down my neck, how can I get my work done?

breathe freely, to have relief from anxiety, tension, or pressure:
Now that the crisis was over, he could breathe freely.
Also, breathe easily, breathe easy.
breathe one’s last, to die:
He breathed his last and was buried in the churchyard.
not breathe a word / syllable, to maintain secrecy; keep a matter confidential:
I’ll tell you if you promise not to breathe a word.
Historical Examples

Benjamin Franklin; Self-Revealed, Volume I (of 2) Wiliam Cabell Bruce
Ramona Helen Hunt Jackson

verb
to take in oxygen from (the surrounding medium, esp air) and give out carbon dioxide; respire
(intransitive) to exist; be alive: every animal that breathes on earth
(intransitive) to rest to regain breath, composure, etc: stop your questions, and give me a chance to breathe
(intransitive) (esp of air) to blow lightly: the wind breathed through the trees
(intransitive) (machinery)

to take in air, esp for combustion: the engine breathes through this air filter
to equalize the pressure within a container, chamber, etc, with atmospheric pressure: the crankcase breathes through this duct

(transitive) (phonetics) to articulate (a speech sound) without vibration of the vocal cords Compare voice (sense 19)
to exhale or emit: the dragon breathed fire
(transitive) to impart; instil: to breathe confidence into the actors
(transitive) to speak softly; whisper: to breathe words of love
(transitive) to permit to rest: to breathe a horse
(intransitive) (of a material) to allow air to pass through so that perspiration can evaporate
breathe again, breathe freely, breathe easily, to feel relief: I could breathe again after passing the exam
breathe down someone’s neck, to stay close to someone, esp to oversee what they are doing: the cops are breathing down my neck
breathe one’s last, to die or be finished or defeated
v.
Also, breathe easily or freely. Relax, feel relieved from anxiety, stress, or tension. For example, Now that exams are over with, I can breathe easy, or Whenever I’m back in the mountains, I can breathe freely again. This idiom originally (late 1500s) was put as breathe again, implying that one had stopped breathing (or held one’s breath) while feeling anxious or nervous. Shakespeare had it in King John (4:2): “Now I breathe again aloft the flood.” The variant dates from the first half of the 1800s.

breathe down someone’s neck
breathe easy
breathe life into
breathe one’s last