adjective
blue, drunk
A1
Main meanings: 'blue' (color) and colloquial 'drunk' (as in 'er ist blau'). Gradable: comparative blauer, superlative am blauesten. Not irregular. Used attributively for color, predicatively for state ("ist blau"). Note idiomatic verb 'blau machen' means to skip work. Common colloquial use in spoken German.
Examples
Das Hemd ist blau.
The shirt is blue.
Nach der Party war er ziemlich blau.
After the party he was pretty drunk.
Das Auto war blau, weil es neu lackiert worden war, und deshalb fiel es sofort auf.
The car was blue because it had been newly painted, and therefore it immediately stood out.
Details
Mnemonics
Picture a clear blue sky to anchor the colour
rhymes with English 'how' but starts with 'bl' like 'blue'
n/a
Notes
Besides the colour meaning, 'blau' colloquially means 'drunk' in German. Context determines meaning.