after having thought about something again.

On second thought we decided that it would be too expensive to fly, so we took a bus instead.

Related vocabulary: but then again, have second thoughts

• the [first/highest/next etc.] rung on the ladder
• the first rung on the ladder
• the first string
• the first thing
• the first thing in the morning
• the flavour of the month
• the four corners of the earth
• the four corners of the world
• the ... from hell
• the front office
• the fruit of loins
• the fruit of your loins
• the full monty
• the funny thing is
• the fur flies
• the game's up!
• the genie is out of the bottle
• the ghost at the feast
• the gift of the gab
• the glory days
• the glory days of
• the glory days of something
• the gloves are off
• the goggle-box
• the good old days