PAL

Ptolemaeus Arabus et Latinus

_ (the underscore) is the placeholder for exactly one character.
% (the percent sign) is the placeholder for no, one or more than one character.
%% (two percent signs) is the placeholder for no, one or more than one character, but not for blank space (so that a search ends at word boundaries).

At the beginning and at the end, these placeholders are superfluous.

rayon‘radius’

French

References: PH Morelon: I.9:3, 28:14
Translation of:
Arabic: نصف قطر [PH Morelon: I.9:3, 29:11]
Synonyms:
le segment issu de son centre jusqu'à sa circonférence[PH Morelon: I.8:1, 26:3-4]