relation

relation, relationship, relatives

As nouns, relation and relative both mean ‘a person related by blood or by marriage’, and both are idiomatic in the plural. For some reason, however, relation is the normal choice in the explicit context of wealth:

• He resented…the mother who had inconsiderately died and left him a poor relation —Julian Symons, 1978.

The state of a person's connection with relations or relatives is his or her relationship, which is also used in the wider context of people's dealings with one another:

• How difficult and unnatural are in-law relationships! —Daily Telegraph, 1970

• You need to consider the quality of the relationship which exists between your son and the teachers, your son and his peers, and between you and the teachers —Where, 1972.

In modern use, relationship has a sexual connotation which should always be borne in mind when using this word:

• She can't forgive me for leaving and I've had to accept that our relationship's finally over —Woman, 1991.

Relation is often preferred to denote the way things (especially concepts and ideas) relate to each other

• (It's now apparent that there's a positive relation between body mass index and the risk of acute coronary events in people with known coronary artery disease —British Medical Journal, 2003)

is the normal choice in meanings to do with activities and procedures, as in the expression business relations, and is the only choice in fixed expressions such as in relation to and bear some (or no etc.) relation to. The plural form relations typically has political connotations, as in good relations, diplomatic relations, foreign relations, etc.