It is used in phonetics with the same meaning:
(phonetics) Of a vowel: made lax.
From A Reference Grammar of Spoken Tamil
By Harold F. Schiffman, Harold F. (university Of Pennsylvania)
Medial Stop Consonants Single stop consonants (i.e. not double or geminated) in medial position (i.e. between two vowels) in Tamil are typically laxed and fricativized. Thus the stop consonants u, (b, rb, l_, ff, a> in medial position are actually ...
From Future challenges for natural linguistics by Jarosław Weckwerth
Lincom Europa, 2002 - Grammar, Comparative and general -
Especially in English /i, e, u/, the first element may be laxed, and in /u, o/, the first element may be laxed or delabialized. American English /u/ is rarely a real |u|; it is more often [uy] or [iu|. and lol is usually [oy] or [ay]. We also have [ij] and [ei] for ...