A tropic hormone is a hormone that stimulates an endocrine gland to grow and secrete it's hormones.(One hormone causes another hormone to do something) In humans, tropic hormones are secreted by the adenohypophysis(anterior pituitary gland).
A few examples of tropic hormones are follicle stimulating hormone(FSH) which helps the female ovaries to mature and ovulate (release an egg).
Adrenocorticotropic hormone(ACTH) which stimulates the adrenal cortex to secrete cortisol.
Thyroid stimulating hormone(TSH) which stimulates the thyroid gland to secrete thyroid hormones.