Frequency: The word is one of the 3000 most common words in English.
1.
Previously means at some time before the period that you are talking about.
Guyana’s railways were ~ owned by private companies...
Previously she had very little time to work in her own garden.
ADV: usu ADV with v, also ADV adj, ADV with cl
2.
You can use ~ to say how much earlier one event was than another event.
He had first entered the House 12 years ~...
= earlier
ADV: n ADV