Full Idea
Any sentence, a single word, or a single component phrase, may often be quite devoid of meaning when separated from its context.
Gist of Idea
Any linguistic expression may lack meaning when taken out of context
Source
Bertrand Russell (Substitutional Classes and Relations [1906], p.165)
Book Reference
Russell,Bertrand: 'Essays in Analysis', ed/tr. Lackey,Douglas [George Braziller 1973], p.165
A Reaction
Contextualism is now extremely fashionable, in philosophy of language and in epistemology. Here Russell is looking for a contextual way to define classes [so says Lackey, the editor].