 Logical constructions differ in whether they involve explicit definitions or contextual definitions, and in the extent to which their result should be described as showing that the constructed object is a mere “fiction”. Russell’s 1901 definition of numbers as classes of equinumerous classes is straightforwardly a case of constructing one sort of entity as a class of others with an explicit definition. This was followed by the theory of definite descriptions in 1905 and the “no-classes” theory for defining classes in Principia Mathematica in 1910, both of which involved the distinctive technique of contextual definition. In a contextual definition apparent singular terms (either definite descriptions or class terms) are eliminated through rules for defining the entire sentences in which they occur. Constructions which are like those using contextual definitions are generally called “incomplete symbols”, while those like the theory of classes are called “fictions.” Russell included the construction of matter, space and time as classes of sense data at the end of his 1924 list. The main problem for interpreting the notion of logical construction is to understand what these various examples have in common, and how the construction of matter is comparable to either of the early constructions of numbers as classes or the theory of definite descriptions and “no-classes” theory of classes. None of the expressions “fiction”, “incomplete symbol” or even “constructed from” seems appropriate for an analysis of the fundamental features of the familiar physical world and the material objects that occupy it.