1.1 Any event in the mind.
1.2 Any event in the mind which put something before the mind.
1.21 Any event in the mind which puts something before the mind as so.
1.22 Any event in the mind which put something before the mind. (See Belief ).
1.3 The process of having thoughts (1.2).
1.3 The process of having thoughts (1.2) in an order which is in agreement with the order of facts (4.2) or the attempt to put thoughts into agreement with facts.
1.5 A group of general properties which a thought (1.2) has.

2.1 The word with the most general sense possible. Anything.
2.2 Those things (2.1) about which other things (2.1) are said.
2.3 A body.
2.4 Anything which has existence for some time.

3.1 A story not put forward as fact (4-1) : See Belief ).
3.2 A thought (2-1) used as if there was a thing (2-4) in agreement with it, when there is in fact (4-2) no such thing.

4.1 Anything which is not so.
4.11 That which makes a thought false when it is false.
4.2 Anything which is (has been, will be).
4.21 Anything complex which is.
4.22 Anything which may be.
4.3 That which a thought in agreement with true thoughts (7-2) is of.
4.4 That which is in agreement with a general thought.

5-001 That which we have knowledge.
5-002 Those processes (Thoughts 1-2) by which we have knowledge.
5-1 A reaction to something.
5-101 That of which we have knowledge -- the causes of our reaction.
5-102 Those processes in us by which we have knowledge.
5-11 Our reaction taken without father reaction to it.
5-12 Our reaction to this reaction.
5-13 Reaction without any events between it and the causes of it.
5-2 An event in the mind,part of the history of a mind, a bit of experience.
5-3 A special relation between the mind (or some event in the mind) and things.
5-4 What is said by an authority not able to make errors.

6-1 A thought taken to be true without being tested.
6-11 A thought taken to be true which is not able to be tested.
6-2 A thought we take as a guide in our acts or feelings.
6-21 A feeling, desire, impulse, tendency in the mind as a guide in our acts or feelings.
6-3 A thought we are certain is true.
6-4 A special feeling which is the cause of our being certain.

7-001. A statement is true : when the thought using it is true.
7-1 . A thought is true when it is in agreement with what it is about.
7-2 . . . . . : in agreement with all other thoughts in comparison with which it may be taken.
7-2l . . . . . in comparison with which it is possible to take it.
7-22 . . . . . in comparison with which it is wise to take it.
7-3 . A thought (feeling, desire, etc. . .) which we have a need to take as a guide in our acts is frequently said to be true.
7-4 . A thought which comes with a feeling like the feelings which come with true (7-l, 7-2) thoughts is frequently said to be true.

8-1 . A general property of a thought by which what the thought is about is fixed.
8-2 . Seeing, hearing, touching, smelling, tasting -— the five senses —- and any other way of getting knowledge which is like them.
8-3 . Good sense.

Cause -— Effect
9-l . C is a cause of B when B does not take place without C.
9-11. Condition. Any event in which we have a special interest in a chain of events on which B is dependent.
9-2 . An event by which another event is forced to take place.
9-21. A pull or push of which we have the feeling when we put bodies in motion (or make an attempt to do so) or when things put us in motion.
9-211. By fiction, the same sort of pull or push looked on as between bodies.
9-212. By fiction, the same sort of pull or push looked on as between things (2-1) which are not bodies -— events, desires, conditions, etc.
9-5 . An example of a general law of the form "With all a, b, c, d’s . . . come e’s".

10-1 . In science, a general fact that with all a, b, c, d’s . . . come e’s.
10-2 . For the Judge, the rule (order, decision, desire) of an authority.
10-21. A statement of a rule or order.

Part, System, Change
11-1 . AB is a part of the system AC.
A B B1 C *_____*_____*_____*

11-2 . When AB1 comes in place of AB, AB is said to be changed to AB1.
11-21. A change is a fiction by which we may give an account of how things are different.
11-22. A change (see Force 9-21) is a special way of feeling we have when one experience takes the place of another.
11-3 . A system is any group of things in any connection with one another.
11-31. A system is that of which something which is said to he changed is taken as a part.
11-32. A sort; any group of things which is made up of things which are the same in some way.
11-4 . A system is any group of properties which any one thing (2-1) has.
11-5 . 'Organic ‘ system. A system is a group of things or properties of one thing such that if any one of them is changed, all the others are changed in some degree by that change.

12-1 . That of which someone is the owner.
12-2 . Anything which anything may be said to be or to have.

13-1 . Existence. ' A is ' == ' A has existence ’. (See Thought 1-21, 1 -22.)
13-2 . Part of a sort. ' A is a B' == ‘ A is a part of the sort B '.
13-3 . Same completely. 'A is B ’ == ' A has all the properties B has, and no others ’.
The sign == is frequently used for ' is ' in 13-3. It has another use which comes from this, when ' A == B ' is taken to say that the two words (or other signs) A and B, though they may be different as words, have the same sense.

14-1 . A thought (or a statement) which is about all the things of a sort is a general thought about them.
14-11. A thought (or a statement) which is about a greater group of things (having a group G as part of it) is more general than a thought about the things in group G, or the things in a part of G.
14-2 . A thought about most hut not all examples in a group is said to be general. Generally == in most examples.
14-21. A statement about a great number of a group of things is a more general statement than one about a smaller number of them.
14-22. Generally == frequently.

15-1 A quality is a property of which a complete account may be given without naming any other thing (2-2) than the one which has the quality.
15-2 Short for ' good quality '.

16-1 A relation is a property which puts two or more things (2-2) into connection with one another.

Necessary -- Chance
17-1 A necessary property is one which a thing has under all conditions.
17-11 That is necessary which, under fixed conditions, takes place (see Cause).
17-12 A way which is the only way (or the best way) to a fixed end.
17-2 A chance property is one which as thing has only under some conditions.
17-3 A chance is what takes place when we have no knowledge of he conditions under which it takes place.
17-31 . . . . . . . when such knowledge as we have makes us ready for some other event.

18-1 Something is possible when hits being so does not make any change in our language machine necessary (16-11).
18-2 That is possible which the rules of our language machine seem to let us say.
18-3 That is possible which is in agreement with our knowledge of things, of fact (4-2).
18-31 That is possible, which, with a change of condition, would not be out of agreement with our knowledge.