To a partial degree or extent, incompletely.
"The sun was partially hidden behind thick clouds during the afternoon storm."
In plain English: Partially means doing something only some of the way instead of all the way.
"The cake was partially eaten by my brother before I got home."
Usage: Use partially to describe an action that has been completed only up to some point rather than finished entirely. It is often confused with partly when describing states of being; use partly for static conditions and partially for dynamic processes involving change over time.
The word partially is formed by adding the suffix -ly to the adjective partial. It entered English as a straightforward modification of an existing term rather than through borrowing or semantic shift.