The word "adventist" refers to anyone awaiting the second coming of Christ.
The word Adventist is the also the official shortened form of Seventh-day Adventist Church which is distinguished by the three angels message, observance of the sabbath and principles underlaid in the Bible
25. Second Coming of Christ:
The second coming of Christ is the blessed hope of the church, the grand climax of the gospel. The Saviour's coming will be literal, personal, visible, and worldwide. When He returns, the righteous dead will be resurrected, and together with the righteous living will be glorified and taken to heaven, but the unrighteous will die. The almost complete fulfillment of most lines of prophecy, together with the present condition of the world, indicates that Christ's coming is imminent. The time of that event has not been revealed, and we are therefore exhorted to be ready at all times. (Titus 2:13; Heb. 9:28; John 14:1-3; Acts 1:9-11; Matt. 24:14; Rev. 1:7; Matt. 24:43, 44; 1 Thess. 4:13-18; 1 Cor. 15:51-54; 2 Thess. 1:7-10; 2:8; Rev. 14:14-20; 19:11-21; Matt. 24; Mark 13; Luke 21; 2 Tim. 3:1-5; 1 Thess. 5:1-6.)
20. Sabbath:
The beneficent Creator, after the six days of Creation, rested on the seventh day and instituted the Sabbath for all people as a memorial of Creation. The fourth commandment of God's unchangeable law requires the observance of this seventh-day Sabbath as the day of rest, worship, and ministry in harmony with the teaching and practice of Jesus, the Lord of the Sabbath. The Sabbath is a day of delightful communion with God and one another. It is a symbol of our redemption in Christ, a sign of our sanctification, a token of our allegiance, and a foretaste of our eternal future in God's kingdom. The Sabbath is God's perpetual sign of His eternal covenant between Him and His people. Joyful observance of this holy time from evening to evening, sunset to sunset, is a celebration of God's creative and redemptive acts. (Gen. 2:1-3; Ex. 20:8-11; Luke 4:16; Isa. 56:5, 6; 58:13, 14; Matt. 12:1-12; Ex. 31:13-17; Eze. 20:12, 20; Deut. 5:12-15; Heb. 4:1-11; Lev. 23:32; Mark 1:32.)
Another answer Nothing. Adventist is just another name for Seventh-day Adventist.