In Sanskrit the words which do not change form with gender, number or person, tense etc. are called avyaya (अव्यय). These avyayas are of 4 main categoris – adverb (kriya visheshan), conjunction, preposition and interjection. Examples of adverb क्रियाविशेषण यदा when तदा then सर्वदा always कदा when सदा always अधुना today इदानीम् now संप्रति nowadays, now अद्य today य्ह: yesterday श्वः tomorrow सायं: evening प्रातं morning शीघ्रं fast दिवा day नक्त: night बहुदा much परश्वः day after tomorrow संभवतः perhaps चिरं everlasting एकदा once कदाचित् sometimes Prepositions : स्थानवाचक अव्यय यत्र here तत्र there कुत्र where सर्वत्र everywhere अन्तः inside बहिः outside अन्तरा in the middle अध: below तत: there समया, निकषा, पार्श्वे nearby इतस्ततः here and there अभित: infront of परितः surrounding, all around अग्रे, पुरतः in front of अन्यत्र elsewhere रीतिवाचक अव...