Secondary, in its most common usage, refers to something of lesser importance or rank compared to a primary or principal entity.
It can also denote something that is derived from or dependent on a primary source or cause. It indicates a supportive or subordinate role, often arising as a consequence or effect of something else.
In education, it signifies the level following primary school. Furthermore, in medicine, it can refer to a condition that results from or is caused by another condition.
Essentially, 'secondary' highlights a dependence or a less central role in a given context, and can often imply a sequential order of occurrence.
EXTRA MINOR LOWLY PETTY
LESSER
AUXILIARY SUBALTERN
SUBSIDIARY
SUBORDINATE JUNIORGRADE
LOWERRANKING
SECONDARYCOIL
SECONDARYWINDING