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.
What Are the Symptoms of Goiter? The symptoms of a goiter include: Swelling at the front side of the base of the neck, ranging from a small lump to a general enlargement. If you have hyperthyroidism (an overactive thyroid gland), symptoms may also include weight loss despite an increased appetite, an increased heart rate, elevated blood pressure, nervousness, diarrhea, muscle weakness, and hand tremors.