This is the 216th most frequent Portuguese word.
necessário
Necessary.
'Necessário' is employed to indicate that a certain action was required due to circumstances.
Foi necessário chamar um técnico para consertar o computador.
It was necessary to call a technician to fix the computer.
Here, 'necessário' is used as a predicative adjective expressing necessity or obligation.
É necessário estudar para o exame.
It is necessary to study for the exam.
'Necessária' is an attributive adjective modifying the noun 'habilidade' (skill), signifying its importance for a condition.