Wendelin and Ursinus define free choice as choosing without compulsion what the intellect shows
Thus Marcus Wendelin, explaining thesis 18 in his Christian Theology (book 1, chapter 5), defines free choice as "a disposition of the will by which, moving itself and without compulsion, it chooses or rejects what the intellect sets before it."
Zacharias Ursinus gives a similar definition in his Catechetical Explanations (part 1, question 8, number 1): "Free choice, then, is a faculty or power of willing or not willing, of choosing or rejecting, an object that the intellect sets before it, by its own movement and without compulsion."
Latin
VI. Sic Marcus Wendelinus Christianae Theologiae lib. 1. cap. 5. in explicatione Theseos 18. liberum arbitrium definit, Voluntatis affectionem, qua proprio suo motu, absque coactione, eligit, vel repudiat rem ab intellectu monstratam. Et huic quoque similis est definitio Zachariae Ursini, Est itaque, inquit, liberum arbitrium facultas, seu potentia volendi, aut nolendi, seu eligendi, aut repudiandi objectum ab intellectu monstratum, proprio motu, sine coactione. In explicationibus Catecheticis, parte 1. quaest. 8. num. 1.