Learn how to say Rhoticity correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word rhotic:
relating to or denoting a dialect or variety of English (e.g. in America and SW England) in which r is pronounced before a consonant (as in hard) and at the ends of words (as in far):
rhotic and non-rhotic speakers
1960s: from Greek rhot-, stem of rho (see rho) + -ic