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.
Symptoms in the neck and thyroid area that can suggest a thyroid problem include: 1  Neck discomfort. 2  Visible thyroid enlargement or lump. 3  Discomfort with ties, scarves, turtlenecks, or necklaces. 4  Hoarseness. Sore throat.  Soreness in 1  neck. Difficulty swallowing.