pain meaning
EN
[peɪn] [-eɪn] 
US WPain
- Pain is an unpleasant feeling often caused by intense or damaging stimuli, such as stubbing a toe, burning a finger, putting alcohol on a cut, and bumping the "funny bone".
- Pain motivates the individual to withdraw from damaging situations, to protect a damaged body part while it heals, and to avoid similar experiences in the future.
- Pain is the most common reason for physician consultation in most advanced countries such as the United States. It is a major symptom in many medical conditions, and can significantly interfere with a person's quality of life and general functioning.
FR pain 
- NounPLpainsSUF-ain
- (countable and uncountable) An ache or bodily suffering, or an instance of this; an unpleasant sensation, resulting from a derangement of functions, disease, or injury by violence; hurt.
- The greatest difficulty lies in treating patients with chronic pain.
- I had to stop running when I started getting pains in my feet.
- NU The condition or fact of suffering or anguish especially mental, as opposed to pleasure; torment; distress; sadness; grief; solicitude; disquietude.
- In the final analysis, pain is a fact of life.
- The pain of departure was difficult to bear.
- NC An annoying person or thing.
- Your mother is a right pain.
- NU OBS Suffering inflicted as punishment or penalty.
- You may not leave this room on pain of death.
- Interpose, on pain of my displeasure. — Dryden
- We will, by way of mulct or pain, lay it upon him. — Bacon
- Labour; effort; pains.
- (countable and uncountable) An ache or bodily suffering, or an instance of this; an unpleasant sensation, resulting from a derangement of functions, disease, or injury by violence; hurt.
- VerbSGpainsPRpainingPT, PPpained
- VT To hurt; to put to bodily uneasiness or anguish; to afflict with uneasy sensations of any degree of intensity; to torment; to torture.
- The wound pained him.
- VT To render uneasy in mind; to disquiet; to distress; to grieve.
- It pains me to say that I must let you go.
- VT OBS To inflict suffering upon as a penalty; to punish.
- VT To hurt; to put to bodily uneasiness or anguish; to afflict with uneasy sensations of any degree of intensity; to torment; to torture.
- More Examples
- Used in the Middle of Sentence
- My headaches come and go, but the pain in my neck is constant.
- If you take this medicine, the pain should ease off after a few hours.
- Served a little to disedge / The sharpness of that pain about her heart. — Tennyson.
- Used in the Beginning of Sentence
- Pain is better than numbness, and broken-heartedness better than stony-heartedness, as surely as it is better to be alive than dead.
- Used in the Ending of Sentence
- The salve made the soreness go away, but with the aches gone I suddenly noticed my other pains.
- There are hueseros, who set bones, and sobadors, who massage away pain.
- However, without the intervertebral disc, the shear stress between L5 and S1 can cause accelerated degradation of the zygopophysis, leading to back pain.
- Used in the Middle of Sentence
Definition of pain in English Dictionary
- Part-of-Speech Hierarchy
- Nouns
- Countable nouns
- Singularia tantum
- Uncountable nouns
- Uncountable nouns
- Countable nouns
- Verbs
- Transitive verbs
- Transitive verbs
- Nouns
Source: Wiktionary
Grammatically, this word "pain" is a noun, more specifically, a countable noun and a singularia tantum. It's also a verb, more specifically, a transitive verb.