This is the 422nd most frequent Finnish word.
mielessä
"In mind" or "on one's mind."
Here, 'mielessä' means 'in mind', specifying that the subject was thinking about something.
Pidin asian mielessä koko päivän.
I kept the matter in mind the whole day.
In this case, 'mielessäni' indicates something being in someone's thoughts or mind, used with a possessive suffix to indicate whose mind.
Minulla on sinut aina mielessäni.
I always have you in my thoughts.
Here, 'mielessä' refers to thoughts occupying one's mind, highlighting contemplation or preoccupation.