n. 1
The condition or fact of suffering or anguish especially mental, as opposed to pleasure; torment; distress
The pain of departure was difficult to bear.
n. 2
An annoying person or thing.
Your mother is a right pain.
v. 1
To hurt; to put to bodily uneasiness or anguish; to afflict with uneasy sensations of any degree of intensity; to torment; to torture.
v. 2
To render uneasy in mind; to disquiet; to distress; to grieve.
It pains me to say that I must let you go.

Related words

Word family: painable painfilled pain-free painkilling painless pain-relieving painsharing painstaking
Phrases: feel someone's pain on pain of period pain referred pain phantom pain back pain feeling no pain nociplastic pain
Is a kind of: sensation

Forms

Plural: pains → troubles, discomforts, miseries, sufferings…
Past participle: pained
e.g. pained → anguished, panged, tormented, tortured…

Pain or Suffering?

Suffering is one of the severer forms of pain. The prick of a needle causes pain, but we should scarcely speak of it as suffering.

J. C. Fernald, English Synonyms and Antonyms (1914)

Use in printed books, per decade from 1850 to 2019.

3 letters: ill¹, woe¹, ile, vex¹
4 letters: hurt¹, bore¹, rack¹, pest¹, ache¹, fret¹, pang¹, toil¹, rend
5 letters: smart¹, upset², wound¹, grief¹, sting¹, agony³, prick¹, annoy², cramp¹, gripe¹, wring¹, chafe¹, dolor, throe
6 letters: effort², suffer², bother², misery³, plague¹, sorrow², stitch¹, offend², aching², grieve¹, harass², harrow², twinge¹, sadden²
7 letters: trouble², penalty³, passion², torture², hurting², anguish², torment², depress², travail², afflict², agonize³, agonise
8 letters: distress², nuisance², irritate³, exertion³, disquiet³, vexation, lacerate³, aggrieve²
9 letters: suffering³, annoyance³
10 letters: punishment³, discomfort³, bitterness³, irritation⁴, affliction³, infliction³, excruciate
11 letters: displeasure³, botheration, painfulness
13 letters: inconvenience⁴

The small number after each word is its number of syllables (upset² = 2 syllables).