| term | meaning (click term for explanation in text) |
| chart datum | height datum to which charted depths are referred |
| charted depth | depth marked on chart |
| diurnal | once a day - a tidal pattern repeating every 24 hours approx |
| drying height | height above chart datum of a point which is sometimes submerged and sometimes dries |
| duration | elapsed time from low water to the following high water |
| ebb | tide going out |
| flood | tide coming in |
| height of tide | height of water above LAT chart datum |
| high water HW | tide fully in, maximum depth of water |
| low water LW | tide fully out, minimumdepth of water |
| lowest astronomical tide LAT | minimum sea level ever expected at low water (in normal atmospheric conditions) |
| mean high water neaps MHWN | mean (average) level of high water, for neap tides |
| mean high water springs MHWS | mean (average) level of high water, for spring tides |
| mean low water neaps MLWN | mean (average) level of low water, for neap tides |
| mean low water springs MLWS | mean (average) level of low water, for spring tides |
| neap range | difference between HW and LW heights during neap tides |
| neap tide | smaller tide, which occurs just after the first and third quarters of the moon |
| range | height difference between successive HW and LW |
| secondary port | a port for which there is no tide table in the almanac |
| semi-diurnal | twice a day - a tidal pattern repeating every 12 hours approx (i.e. twice in 24 hours) |
| slack | period of zero tidal stream |
| spring range | difference between HW and LW heights during spring tides |
| spring tide | larger tide which occurs just after new moon and full moon |
| standard port | port for which full tide tables are published in the almanac |
| stand | period when the water level neither rises nor falls |
| tidal curve | published curve which allows you to predict heights of tide between HW and LW |
| tidal diamond | chart symbol indicating a position for which tidal stream data is provided |
| tidal stream | motion of water caused by flooding or ebbing tide |
| tidal stream atlas | publication which predicts tidal streams for an area, printed on small charts |
| tide table | publication of the times and heights of high and low water |
| universal time UT | standard global time datum (same as GMT for our purposes). Also known as Universal Time Coordinated (UTC) |