Standard Estonian vocabulary is quite rich, as it includes words from both the Northern and Southern dialect areas. The vocabulary is further increased by the frequent word derivations by means of various affixes.

Derivations of the verb nägema 'to see', for instance, are: nägu 'face', nägematu 'unseen, invisible', nägemine 'eyesight', nägemus 'vision', nägemuslik 'visionary', nägevus 'sight', nägija 'seer', nägupidi '(known) by face', nägus 'handsome', nähe 'symptom, indication', nähtamatu 'invisible', nähtav 'visible', nähtaval 'in sight', 'in view', nähtavalt 'obviously', 'clearly', nähtavasti 'apparently', nähtavus 'visibility', nähtus 'phenomenon', nähtu 'something or someone that has been seen', nähtuma 'appear', 'to become clear', etc.

Estonian vocabulary consists of native words plus loan words. But as the Estonian language offers many possibilities of derivation, it would be more correct to speak of native stems and loan stems. Estonian stems are those which the language has in common with other Finno-Ugric languages or are typical for Estonian alone. In the opinion of language scholars, the ratio of Estonian own and the loan stems in Estonian is about 50:50. If one disregards the international words with Greek and Latin stems, the share of words with Estonian stems even reaches two thirds

Standard Estonian has also, throughout its history, been lexically influenced by, for example, French and more recently by the English language. The words are often adapted to the extent that their origin can no longer be deduced:

The majority of Russian loans are centuries old; only few have survived from the last 50 years of Soviet tutelage.