HinKhoj Dictionary

An annual calendar that contains important dates and time - Almanac
A structure on which abstractly defined structure is based - Axiom
Spoken on the spot without any preparation - Extempore
A sentimental memory of the past - Nostalgia
Certain to happen - Inevitable
Safe to drink - Potable

I’d like you to meet someone.मैं आपको किसी से मिलवाना चाहता हूँ।
Sorry to bother you.आपको परेशान करने के लिए माफी चाहता हूं।
As far as I know.जहां तक मुझे पता है।
Frankly speaking...खुलकर कहूं तो...

Epigram - चुटकुला/ सुभाषित (any witty, ingenious, or pointed saying tersely expressed)
He would end his lecture with a summarizing epigram.

Epigraph - पुरालेख/ शिलालेख (an inscription, especially on a building, statue, or the like)
As the statue was unveiled, a beautiful epigraph could be read.

Answer back - reply to someone in an authority role in a rude argumentative style
Back somebody up - to support someone publically
Back up - to take a step backward (literally)
Back up - move backward in time or a conversation (figurative)
Back down - to give up
Back down - to let go of something you are defending in a fight/argument

Alleged: कथित (to say that someone has done something illegal or wrong without giving proof)
Habitat: प्राकृतिक वास (The type of environment in which an organism or group normally lives or occurs)
Invalidate: रद्द करना (Declare invalid)
Liquidation: दिवालियापन (a situation in which an asset is sold in order to get cash)
Mammoth: विशाल (extremely large)