DBA_TAB_COLUMNS

Columns
   ___________________________
 
   OWNER
      The Owner
   TABLE_NAME
      Table,view or cluster name
   COLUMN_NAME
      Column name
   DATA_TYPE
      Datatype of the column
   DATA_TYPE_MOD
      Datatype modifier of the column
   DATA_TYPE_OWNER
      Owner of the datatype of the column
   DATA_LENGTH
      Length of the column in bytes
   DATA_PRECISION
      Length: decimal digits (NUMBER) or binary digits (FLOAT)
   DATA_SCALE
      Digits to right of decimal point in a number
   NULLABLE
      Does column allow NULL values?
   COLUMN_ID
      Sequence number of the column as created
   DEFAULT_LENGTH
      Length of default value for the column
   DATA_DEFAULT
      Default value for the column
   NUM_DISTINCT
      The number of distinct values in the column
   LOW_VALUE
      The low value in the column
   HIGH_VALUE
      The high value in the column
   DENSITY
      The density of the column
   NUM_NULLS
      The number of nulls in the column
   NUM_BUCKETS
      The number of buckets in histogram for the column
   LAST_ANALYZED
      The date of the most recent time this column was analyzed
   SAMPLE_SIZE
      The sample size used in analyzing this column
   CHARACTER_SET_NAME
      Character set name
   CHAR_COL_DECL_LENGTH
      Declaration length of character type column
   GLOBAL_STATS
      Are the statistics calculated without merging underlying partitions?
   USER_STATS
      Were the statistics entered directly by the user?
   AVG_COL_LEN
      The average length of the column in bytes
   CHAR_LENGTH
      The maximum length of the column in characters
   CHAR_USED
      C if the width was specified in characters,B if in bytes
   V80_FMT_IMAGE
      Is column data in 8.0 image format?
   DATA_UPGRADED
      Has column data been upgraded to the latest type version format?

Related:

 DBA_ALL_TABLES         ALL_ALL_TABLES        USER_ALL_TABLES
 DBA_PART_TABLES        ALL_PART_TABLES       USER_PART_TABLES 
 DBA_TABLES             ALL_TABLES            USER_TABLES          TAB 
 DBA_TAB_COLUMNS        ALL_TAB_COLUMNS       USER_TAB_COLUMNS 
 DBA_TAB_COLS           ALL_TAB_COLS          USER_TAB_COLS 
 DBA_TAB_COL_STATISTICS ALL_TAB_COL_STATISTICS USER_TAB_COL_STATISTICS 
 DBA_TAB_COMMENTS       ALL_TAB_COMMENTS      USER_TAB_COMMENTS 
 DBA_TAB_HISTOGRAMS     ALL_TAB_HISTOGRAMS    USER_TAB_HISTOGRAMS 
 DBA_TAB_MODIFICATIONS  ALL_TAB_MODIFICATIONS USER_TAB_MODIFICATIONS 
 DBA_TAB_PARTITIONS     ALL_TAB_PARTITIONS    USER_TAB_PARTITIONS