Firstly there have never in the last two hundred years been worldwide gatherings of all the bishops, and it is unlikely to happen as there are simply too many bishops to make this feasible. Gatherings of Bishops are typically done at the province or country level.
The Catholic church does however hold regular meetings of the Pope and All the Cardinals (who are also bishops).
The consistory is a formal meeting of the Sacred College of Cardinals of the Roman Catholic Church, except when convened to elect a new pope (in which case the meeting is called a conclave, and special rules of membership, procedure, and secrecy apply).
Consistories are held in Vatican City for taking care of the business of the college, which usually involves advising the Pope on important matters concerning the church.
Consistories are of three kinds: secret or ordinary, public or extraordinary and semi-public.
A synod (also known as a council) is a council of a church, usually a Christian church, convened to decide an issue of doctrine, administration or application. An ecumenical council is so named because it is a synod of the whole church.
Unless the meeting is a synod or a council (see above), it is simply called a meeting.
The secret meeting held to elect a new pope is called a conclave - meaning 'with a key' indicating that the cardinals are locked in to the meeting and nobody may enter or leave unless it is an emergency situation.
Ecumenical Council.
It is called a synod or a council.
A synod
Ecumenical Council
Bishops that elect the pope are called cardinals.
All cardinals under the age of 80 elect the new pope in a secret meeting in the Sistine Chapel called a conclave..
A conclave is a secrete meeting of the cardinals held in the Sistine Chapel to elect a new pope.
It is called a conclave.
The cardinals use paper ballots to elect a pope. There are no voting machines used.
2/3 of the eligible cardinals (under age 80) are needed to elect a pope.
The Sistine Chapel is where the Cardinals meet to elect a new Pope.
The College of Cardinals
It is called a conclave and it is held in the Sistine Chapel.
The College of Cardinals elect the pope.
Cardinals elect Popes, but they are not necessarily bishops.
The Pope gets elected by the Cardinals not the people.