I. my¹ S1 W1 /maɪ/ determiner [possessive form of ‘I’]

1. used by the person who is speaking to show that something belongs to or is connected with himself or herself:
Have you seen my car keys?
My mother phoned last night.
I’m sure you don’t want to listen to all my problems.
Even my own family wouldn’t believe me.
an apartment of my own

2. my goodness/my God etc used when you are surprised or shocked about something:
Oh my God! I’ve missed the train.

3. my dear/darling/love etc used when talking or writing to someone that you love or like a lot:
Happy Birthday, my love.

[TahlilGaran] Dictionary of Contemporary English ▲

II. my² interjection
used when you are surprised, impressed, or upset:
My! Look at the size of that tree!
‘It’s 3:30.’ ‘Oh my, I’m going to be late!’

[TahlilGaran] Dictionary of Contemporary English ▲