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.
A swelling or enlargement in the neck is a visible clue that something may be wrong with the thyroid. A goiter may occur with either hypothyroidism or hyperthyroidism. Sometimes swelling in the neck can result from thyroid cancer or nodules, lumps that grow inside the thyroid.air loss is another sign that thyroid hormones may be out of balance. Both hypothyroidism and hyperthyroidism can cause hair to fall out. In most cases, the hair will grow back once the thyroid disorder is treated.