Gather, collect, assemble, congregate mean to come or to bring together so as to form a group, a mass, or a unit.
The same distinctions in applications and in implications characterize their derivative nouns gathering, collection, assemblage (which see) or assembly, congregation. Gather is the most widely applicable of these words; it may be used in reference not only to persons and objects but to intangible things.
In certain phrases gather acquires additional specific connotations; thus, gathering flowers or crops implies plucking and culling as well as bringing together; gathering a ruffle implies a drawing together or into folds on a thread; gathering one’s wits connotes an effort at concentration or at mustering or rallying mental forces.
Collect is often used in place of gather with no intended difference in meaning. But collect may convey, as gather does not, the ideas of careful selection or a principle of selection, of orderly arrangement, or of a definitely understood though not always expressed end in view; thus, to collect butterflies implies a selection of specimens and, usually, their cataloguing; to collect books (as in book collector ) implies a choice of books with regard to some such principle as rarity, beauty of binding, or authorship.
There is a subtle difference between to gather one’s thoughts, which often merely implies previous scattering, and to collect one’s thoughts, which implies their organization; there is also a difference between to gather money, which may mean merely to accumulate it, and to collect money, which usually suggests either raising a fund by gifts, subscriptions, and contributions or taking action to obtain possession of money due. Collect and collection are often preferred to gather and gathering when various things are brought together; thus, a jumble or an omnium-gatherum is a miscellaneous collection rather than a gathering; collect rather than gather enough chairs for all the guests to sit down.
Assemble stresses more emphatically than either gather or collect a close union of individuals and a conscious or a definite end in their coming or in their being brought together. It is used chiefly in reference to persons who gather together, either of their own will or at the call of another, so as to form a group or body that will unite in action or join in counsel or discussion.
In reference to things assemble implies an agent who collects them in order to unite them into a single body or structure or into a distinct and isolated group; thus, the assembly department of an automobile plant is the department in which the workmen build the cars by assembling the component parts made in other departments or in other factories.
Congregate implies a flocking together into a crowd, a huddle, or a mass.
Congregation is specifically applied to an assembly meeting for religious worship, but it usually retains the suggestion of a crowd that has flocked together.