Bound noun used mainly in formal or written contexts; not a standalone word for everyday 'thought'. Often appears in compounds like 思考 (thought process) or 参考 (reference).
「考」という字は、考えるという意味を含んでいる。
The character 考 includes the meaning of thinking.
report on one's investigation into ...
Suffix used in academic or formal titles, e.g., 〜考 meaning 'a study of ...' or 'thoughts on ...'. Not productive in everyday speech.
彼の論文の題名は「日本古代史考」だった。
The title of his thesis was 'A Study of Ancient Japanese History'.
Rare, archaic suffix used in formal or literary contexts to refer to one's late father, e.g., 先考. Not used in modern conversation.
墓碑に「先考」と刻まれているのを見たことがある。
I have seen '先考' (deceased father) inscribed on a tombstone.
考え is the natural standalone word for 'a thought' or 'an idea' in everyday speech, whereas 考 alone is rarely used outside formal compounds or titles.
考 (こう) means 'thought/consideration' while 講 (こう) refers to a lecture or discourse; the two share a reading but differ completely in meaning.
The kanji 考 originally depicted an old person leaning on a stick, associated with 'aged' and later extended to 'think' or 'consider'. The reading こう is the on'yomi.
archaeology; study of antiquities
reconsideration; rethinking; review
historical investigation; study of historical evidence
careful consideration; deliberation; thinking over carefully
study; discussion; research article; academic paper
examination; test; assessment
consideration; thought; rethinking
long thought; lengthy consideration; pondering for a long time
one's late father
consideration; deliberation; thinking over
miscellaneous studies; collected investigations
misunderstanding; mistaken idea
momentary thought; brief consideration · one's humble opinion; one's thoughts
foolish thought; stupid idea · (one's own) thought; (one's own) idea
surmising; speculation; conjecture
deceased father of the current emperor
deceased grandfather; deceased father and grandfather · distant ancestor; forefather
one's own thoughts; personal opinion; personal view