These words refer to any actions that prevent something from pursuing its natural or intended course forward. Delay may suggest either a slowing down of movement or a temporary but full stop in a forward motion. Detain , in contrast, suggests a longer, possibly permanent halt. Retard , in distinction from both, suggests a considerable slowing down of movement but not necessarily a halt at all; it is also more formal than delay or detain .

• I was delayed several times on my walk by people seeking my name on various petitions; I was detained from keeping our appointment by a business conference that lasted most of the day; Economic progress in Latin America has been consistently retarded by a high birth rate.

Hold is more informal than the previous words but also implies direct intervention and possible physical contact: It is often followed by back or up : a man who would have joined the fight but for two friends who held him back ; a flight that was held up for several hours because of poor visibility. As can be seen hold suggests the temporary full stop possible for delay . Keep also hares this suggestion; it often appears with out and back and suggests the imposition of a barrier, not necessarily physical, that must be removed before progress can be resumed.

• He was kept from entering the burning house by several neighbours; She was kept from speaking out by her distaste for unpleasant scenes; They were kept out of the square by the large demonstration that was under way; Traffic was kept back by hastily erected barricades.