Until the mid 20th c. in most of philosophy related publications it was agreed that Plato and subsequent reasearch dealt with "Ideas" - a word adapted from his original Greek. Some 50 years later the usage has shifted to the use of a latin substitute "Form". Of course this happened in the English speaking world but now it is spreading elsewhere.
Is there a short meaningful explanation why this substitution has been made?
There is an obvious incongruity in the replacement as the latin "form" appears to be derived from the Greek "morphe" which is its exact equivalent. Aristotle is no less influential in philosophy and form/morphe is a key term in his work. Calling Plato's ideas 'forms' obviously creates confusion and problems for viewing and understanding all the subsequent tradition. Who benefits from it? (Currently in SEP one can read the literal nonsense: “hylomorphism”, a portmanteau of the Greek words for matter (hulê) and form (eidos or morphê).!)
PS. The Dictionary of Untranslatables (Cassin, 2014, p. 2729-2744) has a remarkable article "Species" which treats the Latin choices for Plato's terms. Also some 700 pages of proceedings from a Philosophie de la forme: eidos, idea, morphé dans la philosophie grecque des origines à Aristote, ed. A. Motte, et al (Louvain: Peeters, 2003). All this is fascinating but does not explain the abrupt contemporary change in terms.