I believe they mean that the random variables have a common support. For example, if X ~ Unif[0,2] and Y ~ Unif[1,3], then their respective PDF's overlap in the interval [1,2], meaning the only interval where both X and Y can have common values is [1,2]. To illustrate, below is a representation of the supports of X and Y, below which is a representation of the real line.
1 Thyroid cancer is a malignant tumor of the thyroid gland. 2  Symptoms of thyroid cancer include swelling in the neck (goiter), neck pain, hoarseness, swallowing and breathing problem, swollen lymph gland in the neck.
Call your doctor if you have any of these signs of thyroid nodules: Swelling in your neck for more than 2 weeks. A hoarse or scratchy voice that is not caused by a cold or throat infection and lasts longer than 1 month. A hard time swallowing. Symptoms of a thyroid problem, such as feeling tired, weak, or nervous; losing weight; having trouble sleeping; or having a fast heartbeat.