‘We will consider next the question what is implied by saying that a person “understands” a word, in the sense in which one understands a word in one’s own language, but not in a language of which one is ignorant. We may say that a person understands a word when (a) suitable circumstances make him use it, (b) the hearing of it causes suitable behaviour in him. We may call these two active and passive understanding respectively. Dogs often have passive understanding of some words, but not active understanding, since they cannot use words.
It is not necessary, in order that a man should “understand” a word, that he should “know what it means,” in the sense of being able to say “this word means so-and-so.” Understanding words does not consist in knowing their dictionary definitions, or in being able to specify the objects to which they are appropriate. Such understanding as this may belong to lexicographers and students, but not to ordinary mortals in ordinary life. Understanding language is more like understanding cricket*: it is a matter of habits, acquired in oneself and rightly presumed in others. To say that a word has a meaning is not to say that those who use the word correctly have ever thought out what the meaning is: the use of the word comes first, and the meaning is to be distilled out of it by observation and analysis. Moreover, the meaning of a word is not absolutely definite: there is always a greater or less degree of vagueness. The meaning is an area, like a target: it may have a bull’s eye, but the outlying parts of the target are still more or less within the meaning, in a gradually diminishing degree as we travel further from the bull’s eye. As language grows more precise, there is less and less of the target outside the bull’s eye, and the bull’s eye itself grows smaller and smaller; but the bull’s eye never shrinks to a point, and there is always a doubtful region, however small, surrounding it.’ (Bertrand Russell, ‘Words and Meanings’ cited in ‘Selected Papers of Bertrand Russell, p. 358-359)