Language/Standard-estonian/Grammar/Adverbs

While in English adverbs are usually formed by adding (-ly) to adjectives. In Estonian many adverbs are formed from adjectives, simply by using the ablative case of the adjective.

Examples:

• Aeglane (slow) becomes aeglaselt (slowly)
• Kaunis (beautiful) becomes kaunilt (beautifully)

However that’s not always the case. Some words are adverbs by nature.

Examples:

• Nüüd (now),
• tõesti (really),
• varsti (soon)

Source: http://mylanguages.org/estonian_adverbs.php