Connascence of type is when multiple components must agree on the type of an entity. In a statically typed language, these issues are often (but not always) caught by the compiler. Consider the following trivial C++ code:

std::string cost;

cost = 10.95; // OOPS!

Dynamically typed languages typically suffer from less obvious instances of connascence of type. Consider a function that calculates your age, given your day, month, and year of birth:

def calculate_age(birth_day, birth_month, birth_year):
    # do the calculation here:

How is this function supposed to be called? Here are a few different options:

calculate_age(1, 9, 1984)
calculate_age(1, 9, 84)
calculate_age('1', '9', '1984')
calculate_age('1', 'September', '1984')