The terms cousin brother and cousin sister are not used in standard British English. Nowadays they are used in Sri Lanka to refer to any male cousin or female cousin respectively, but the origin of the term lies in the traditional distinction between cross cousins and parallel cousins.
There are many different terms in both Sinhala and Tamil for aunts and uncles and cousins, and because English does not have equivalent terms, the Sinhala/Tamil words tend to be used in Sri Lankan English as well. This is my understanding of the system, though of course there are regional variations, and different families might have their own terms for particular family members.
1. Your mother’s elder sister is your loku amma (Sinhala)/ periyamma (Tamil). Your mother’s younger sister is your punchi amma (S)/ sinnamma (T) â€“ or affectionately, punchi (S)/ sitti (T). Your father’s elder brother is your loku thaaththa (S)/ periyappa (T), and your father’s younger brother is your baappa (S)/ chittappa (T).
2. Your mother’s brother (elder or younger) is your maama (in both Sinhala and Tamil). Your father’s sister (elder or younger) is your nenda (S)/ maami (T). Your maama could also be your uncle by marriage (your nenda/maami’s husband), and your nenda/maami could also be your aunt by marriage (your maama’s wife).
Note the distinction that is made between maternal aunts and paternal uncles (para 1) and paternal aunts and maternal uncles (para 2). Traditionally, you have a closer bond with your loku amma/punchi amma/loku thaaththa/baappa than you have with your nenda/maama. And this distinction applies to the next generation as well, where you have a closer relationship with those cousins who are the children of your maternal aunts and paternal uncles (your parallel cousins), than with the children of your paternal aunts and maternal uncles (your cross cousins). You might refer to your parallel cousins as ayya/akka/malli/nangi (Sinhala) or anna/akka/thambi/thangachchi (Tamil), the same terms you use for your own brothers and sisters, while your cross cousins are your massina/naena (S) or machchaan/machchaal (T).
Such distinctions are not necessarily made in most families nowadays, especially in more urban and/or westernised contexts. But one area where it still applies is when it comes to marriages between first cousins, which used to be much more common than they are today. According to custom you can marry one of your cross cousins, but not one of your parallel cousins, who are considered as your own brothers and sisters (hence the origin of the terms cousin brother and cousin sister).
There is no biological or genetic reason why a marriage between cross cousins should be preferable to a marriage between parallel cousins. And most legal systems do not make the distinction either, including Sri Lanka, where all first cousin marriages are legal. And yet it is a common custom which is found, with variations, in several cultures throughout the world, including South India.
Many of the terms mentioned above can also refer to your in-laws. Your father-in-law is your maama (S/T), and your mother-in-law is your nenda (S)/ maami (T). This is very logical when you think that if you married your cousin (cross cousin of course), then your mother’s brother (maama) would be your father-in-law, or else your father’s sister (nenda/maami) would be your mother-in-law. And since one of your own brothers or sisters might marry one of your cross cousins (are you still with me?), the term massina (S)/machchaan (T) can also refer to your brother-in-law, and the term naena (S)/ machchaal (T) can also refer to your sister-in-law.
A-Z of Sri Lankan English isÂ an all-new, occasional alphabetical dipÂ into the variety of English spoken in Sri Lanka, published exclusively onÂ Groundviews. The original A-Z of Sri Lankan English was published in the travelsrilanka magazine, and can be found here.