Collocations

The grouping or juxtaposition of things, especially words or sounds.

Such a specific grouping.

A sequence of words or terms that co-occur more often than would be expected by chance (i.e., the statistically significant placement of particular words in a language), often representing an established name for, or idiomatic way of conveying, a particular semantic concept.

A method of finding an approximate solution of an ordinary differential equation L[y]=0 by determining coefficients in an expansion y(x) = y_{0}(x) + \sum_{l=0}^{q}\alpha_{l} y_{l}(x) so as to make L[y] vanish at prescribed points; the expansion with the coefficients thus found is the sought approximation.