Hell: A place of punishment (Matthew 25:41, 46; Revelation 19:20). Hell is eternal (Matthew 25:46). Those who reject Jesus Christ, if they die without accepting Him as their Lord and Savior, will go to Hell forever (Revelation 20:11-15, 21:8). Those who accept Jesus Christ before they die will live for eternity with Him (John 11:25, 26; 2 Corinthians 5:6).
Rapture: The rapture of the church will happen when God “snatches away” all believers from the earth to make way for His righteous judgment to be poured out on the earth during the tribulation period. For more details see: http://www.gotquestions.org/rapture-of-the-church.html
Righteousness: The state of moral perfection required by God to enter Heaven; righteousness means without guilt or sin. God cannot let us into heaven with guilt and sin in our lives, which is why He sent Jesus Christ to die for our sins. “For this is how God loved the world: He gave his one and only Son, so that everyone who believes in him will not perish but have eternal life” John 3:16 (NLT). Jesus’ Blood washes away our sins—as soon as we commit our lives to Him. Only then can we enter Heaven. God cannot let imperfect, sinful people enter perfect Heaven. God wants ALL of us to be in Heaven with Him, but you have to accept Jesus Christ as your Lord and Savior in order to enter Heaven.
Please see this link to learn what the word perish means in John 3:16: http://bdcministries.com/2010/11/15/what-does-it-mean-to-perish/
Tribulation/Great Tribulation: A future period of time when God will finish His discipline of Israel and finalize His judgment upon the unbelieving (non-Christian) people of the world. For more details see: http://www.gotquestions.org/tribulation.html
Saved: One who has personally and deliberately determined to believe in Jesus Christ, trusting in Him, and Him alone.
Resource note: The Biblical quotations in a variety of translations were taken from www.biblegateway.com.