Merriam-Webster.com

: of or relating to Arminius or his doctrines opposing the absolute predestination of strict Calvinism and maintaining the possibility of salvation for all

likewise definition for arminianism

Etymonline.com

Arminian (adj.)

1610s in reference to a Protestant sect, from Arminius, Latinized form of the name of James Harmensen (1560-1609), Dutch Protestant theologian who opposed Calvin, especially on the question of predestination. His ideas were denounced at the Synod of Dort, but nonetheless spread in the Reformed churches. As a noun from 1610s. Related: Arminianism.

Discussion/Explanation

The Arminian position or Arminianism continues to be a long-standing opponent to those of the Calvinist persuasion. Much of the differences stem for opposing vies on man’s will–particularly man’s will involved in salvation. From this, there is a natural domino effect on related doctrines such as predestination.

Today, we cannot say that either side of the debate is monolithic as there are plenty with derivative or offshoot beliefs. Arminians will often state there is a synergy combining the working of God in people’s hearts (regeneration) and man’s will then choosing or not choosing to follow God. The model is therefore God’s works + man’s choice.

However, there are those who consider themselves Arminian or, at least, side with them who, in practice or belief, drop the synergy and opt more for a Pelagian view in which man’s will dominates. These people tend to cut off God’s involvement after Christ’s payment on the cross and leave everything afterward in the realm of man’s choice. Pelagius did this too though he took it to the point of effectively making God merely responsive to our wills, thereby gutting God’s sovereignty/plan/etc.