One word substitution definition, example

One word substitution is a replacement for a long and lengthy sentence or definition.

It falls under the category of vocabulary as words, sentences, and definitions are part of speech. 

Nostalgia (पुरानी याद)	A sentimental memory related to the past.
Utopia (आदर्श लोक)	An imaginary society free from crime and poverty.
Infallible (अचूक)	Incapable of making mistakes.
Crusade (धर्मयुद्ध)	A vigorous campaign for a cause.
Democracy (लोकतंत्र)	A govt led by all the eligible candidates through election.
Aviary (चिडयाघर)	A cage/ place mode for birds.
Cemetery (कब्रिस्तान)	A burial ground
Claustrophobia (छोटी/तंग जगह का डर)	Fear of closed place
Palaeography (प्रचीन शिलालेखों)	Study of ancient writing and scriptures
Shoal (मछिलयों का समूह)	A number of fish swimming together.
Narcissist (आत्ममुक्त)	A person who loves himself the most.
Pessimist (निराशावादी)	The person who looks at the negative dark side of everything.
Lexicography (कोश-रचना)	The practice of writing dictionaries.
Caravan (काफिला)	A number of people traveling together,
Polyglot (बहुभाषी)	Someone who speaks more than one language.
Posse (सिपाहिओं का समूह)	A temporary police force.

Optimist आशावादी	The one who looks at the brighter side of everything.
Gym (व्यायामशाला(	A place to exercise and training.
Calligraphy (हस्तलिपि विद्या)	The act of producing beautiful handwriting.
Omniscient (सर्वज्ञ)	The who knows everything.
Omnipresent (सर्व-भूत)	The one who is present in everything.